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Chapter Text

His first memory is of blue eyes. 

They are startling, overly bright and indescribably deep, the kind of eyes one can't possibly look away from again, where a single glimpse is already enough to turn an accidental glance into an involuntary stare. 

The kind of eyes one simply doesn't forget—except when one is forced to.

He can remember again how wild and intense they always were; even more so right now, as they fill with tears, glimmering droplets of saltwater collecting in a ring of dark lashes, only just managing to stop themselves from rolling down a pair of slightly chubby cheeks.

In his first memory, Sirius does not blink. He simply stares down at Regulus with tears in his eyes, his expression so full of love and adoration that its easy meaning seems almost complicated. 

Sirius looks at him as if Regulus is a creature of wonder, as if he would do anything in his power to protect him. As if he would burn down the world and invent new forces to break the law of destiny. As if his world has just shifted fundamentally in order to accommodate to his new meaning, to his little brother.

When did he stop looking like that? Regulus questions, mourning and grieving and shifting and breaking and healing and coming apart in the same way he comes together. 

He didn't expect his chest to split open once the wall inside his mind finally came down, but it does so anyway. His mind bleeds memories the way his body once bled blood, cruelly and dangerously, tainting the world around him as he loses himself. He tries to hold himself together—he really does—but his hands are heavy and his screams are silent, and this time, no one is around to catch him when he falls to the floor, crumbling and collapsing, tremors wrecking his shape as he breaks and breaks and breaks and cracks.

Clean in two at first, and then again and again and again, until he is a thousand pieces once lost, a million memories once forgotten. He is not himself anymore, but he never was. 

He is the past and the future and the present and he is dead and alive and hurting and in peace and somehow everything is the same. None of it matters.

Blue eyes are everywhere, in all of his memories—because he was always there, his brother, and Regulus wonders how on earth anything in this world managed to make him forget.

***

He is one and a half years old, staring at his brother in concentration as his very first word stumbles out of his mouth, clumsily and a little slurred. 

It is "Siri," and it makes Sirius' blue eyes go wide with unperturbed wonder. His breath hatches, caught inside his chest, stuck in his throat, locked into his small body.

Regulus' second word is "Siwius," immediately following his first attempt but still putting a displeased frown on his little toddler face because he can't quite get it right.

It's a difficult name to pronounce—which fits the boy it belongs to, because nothing about Sirius has ever been easy.

His brother doesn't seem to mind Regulus' struggles with his name though. Instead, he grins down at him with unabashed joy, excitement visible in every line of his face as he gathers Regulus into his small arms. His touch is soft, careful; he hasn't yet lost the wonder that takes ahold of him every time his gaze settles on his younger brother, hasn't yet lost the fear of accidentally shattering him with the force of his love.

"That's me," he tells Regulus, speaking into his growing curls, beaming with happiness, and Regulus scoffs even at one and a half years old—because of course it is him. As if Regulus would need a reminder of who Sirius is; as if Regulus could ever forget.

Giggling now, Sirius presses a wet kiss on Regulus' forehead, causing the latter to start pretending to wiggle away in annoyance, even as he is clearly grinning from ear to ear. 

"Siri," he complains, shaking his head no—which settles the ground for their future relationship because Sirius, respectively, does indeed not stop pestering him. 

He chases after his younger brother relentlessly instead, winds careful arms around him over and over again, peppers him with kisses until they are both caught in that delirious state of cry-laughing that only children in love and peace ever tumble headfirst into. 

"Love you," Sirius tells him afterwards, when they are but two tiny bodies, spent as they rest on the scratchy carpet in Sirius' room. 

Curiously, Regulus turns his head towards his brother—because that's what he always says to him, and Regulus hasn't yet fully figured out the meaning behind the words, but he thinks poking Sirius' elbow might be a fitting response. He must be right; because Sirius smiles, all crooked teeth and sparkling eyes, mischief in the making as he staggers up onto his feet, his restless mind already set on a new adventure.

"Siwius," Regulus hums in support, following his movements with tired eyes—because at one and a half, his brother's name and the word love still mean exactly the same to him. Because his world starts and ends with Sirius.

His eyes flutter closed.

***

He is four years old and shaking. Sirius' hand is shaking too, his palm flat out towards Regulus as he stands between him and their mother, acting like an insurmountable wall instead of just a little boy. Regulus tries to peek out from behind Sirius' back, tries to understand what is going on, but his eyes are swimming with tears, an ocean ready to be unleashed for drowning, and he doesn't see much, in the end.

He knows their mother's face, though. Knows it is brimming with rage, with anger, with something he has already learned to associate with incoming pain. He knows that the next few minutes will hurt—and he is scared because he doesn't understand why. 

"It was me," Sirius insists, squaring his little shoulders as he fixes a grin onto his pale face. 

Regulus can hear the taunting smile in his voice—and he doesn't yet fully understand the intricacies of lying, can't yet fully grasp what Sirius keeps doing for him, but his terrified hiccups calm down a little, his brother's smile all the reassurance he needs.

"Stupid boy," their mother snarls, icy blue eyes sparkling with fury when Regulus finally manages to catch a glimpse of her. So cold, so harsh. 

She looks a lot like Sirius, but she doesn't sound much like him. Doesn't act like him either. His mother isn't the one tutting at Regulus' bruises in exasperated concern when he keeps knocking into tables and dressers, isn't the one poking his stomach until he aches with laughter, isn't the one who makes sure he is tucked in at night, when coldness seeps in from the badly insulated windows. She doesn't check his forehead for a temperate when he grows a little too quiet, doesn't sing him back to sleep when a nightmare wakes him up and leaves him teary-eyed and feeling hollow.

That's all Sirius.

Sirius, who spends his evenings murmuring terrifying stories about large monsters creeping into old houses to steel the youngest children right out of their beds—but who also stays up for hours afterwards, indulgently getting up to check every closet und dark corner that Regulus points out to him from where he is hiding underneath Sirius' covers, breathing in the warm certainty that his brother will keep him safe, even if he can't help but scare him at first. 

Sirius, who once told him exactly that. "We protect each other," he explained, words slurring as he tried to figure out how to talk without ripping his freshly acquired split lip open again while Regulus stared at him, wide-eyed and concerned but nodding along because he was still at that age of believing every single one of Sirius' words. "That's what brothers do, Reggie."

Sirius, whose shaking shoulders now gradually steady as he gestures behind his back, urgent hand movements telling Regulus to leave—and he does. Bolts backwards quickly, runs past what was once their mother's vase and is now nothing more than a collection of broken shards. Bright glass that shattered to the sound of juvenile giggling during a relentless game of tag and will disappear again to the sound of muffled cries, made by a small body pushed by large hands.

He hides in Sirius' room, the safest place in this house. With his whole body tugged under their blankets, Regulus strains his ears to try and pick up anything other than the sound of his own scared breathing. He can't. Sirius—always so loud and boisterous and full of life—has already learned when to keep quiet. 

It takes a while for Sirius to join him under the blankets. He is bleeding when he does—from a dozen cuts on his arms and hands, some small and shallow, others deeper and haphazardly sealed with bandaids—but he is smiling. Proud and wicked, like the knight he pretends to be. Like the knight he is, to Regulus.

"You wanna hear a story?" his brother whispers, blue eyes glinting dangerously, never dull, never sad, never tired, even when Regulus shakes his head in answer.

He's had enough of monsters for today. 

"'m sorry," he sniffs, pressing his face against Sirius' shoulder, hoping his brother doesn't hate him. 

He doesn't fully understand where the cuts came from, can't quite wrap his head around the difference between pushing and falling—but there's a sinking feeling in his stomach that he will grow up to name guilt. 

He keeps seeing their mother's face on the back of his closed eyelids, furious and frantic for all the wrong reasons, keeps seeing the vase wobble once, twice, before it tumbled to the ground and shattered. Keeps seeing the brief slip of Sirius' wild smile, that small flash of dread in his eyes as both of them paused their movements, frozen in alarm.

"Don't be," Sirius murmurs now, petting his hair, mindlessly untangling his curls. "You didn't mean to." He leans closer, voice dropping in that way it does when he chooses to share another secret, and Regulus holds his breath in anticipation, his cries already forgotten—because Sirius' secrets are rare, and special, and his. "You know, I never actually liked that vase."

"It was so ugly," Regulus agrees immediately, and then both of them are giggling because it is better than crying, and it's always one of the two, in their house.

Over the next few days, Regulus meticulously studies the way Sirius' cuts heal closed again. He draws little smiley faces onto his brother's bandaids while Sirius sighs and rolls his eyes but clearly not-so-secretly enjoys the attention, and it's almost enough for the weight in his stomach to settle again. 

Just not quite.

He is more careful around the house, afterwards. Watches his steps the way he watches his back, looks down at his feet instead of up into the sky. Declines Sirius' constant invites to games that most definitely shouldn't be played inside and pretends not to notice how his brother starts scowling a little more with every new shake of his head—because he is taking it seriously now, protecting his brother. Because that's what brothers are supposed to do. Because Regulus hasn't yet figured out how to repay Sirius for each and every one of his sacrifices, but he will, in the future. He'll make sure of it.

***

He is six years old. It's not the first time his mother has hit him, but it's the first time that had him begging her to stop. 

She didn't, of course. His mother doesn't like being told what to do. She's a bit like Sirius, in that way—just...not really.

All afternoon, Regulus has been avoiding his brother. It's not the easiest feat in the world, but it is worth the trouble, he thinks, because he can't let him see. Sirius is still so much better at the whole protecting thing, takes care of him loudly while Regulus gets lost in quiet scheming that often goes nowhere. He is doing his best—they both are; he knows—and for the past six hours, Regulus' best had been to keep Sirius from finding out what happened. 

It was his fault, anyway; a stupid slip, a dumb mistake, something he should have known better—and it won't work very long, the whole keeping-Sirius-in-the-dark thing, but Regulus had hoped for it to work for longer than just a single afternoon, at least. It had been hard work, to keep quiet. He had to muffle his cries, had to remind himself what he was doing this for, and who.

Now though, as he stands in front of his brother's door, the faint sound of music concealing his arrival, he just wishes he would have gone straight to him. The pain always gets worse when night falls, he knows that. Somehow though, he wasn't prepared for it today.

There are silent tears rolling down his cheeks, disappearing into the already damp collar of his shirt as he stands in the hallway, his fist raised while he wills himself to be brave enough to knock. 

He'll be mad, Regulus thinks, and it scares him. 

Sirius lives in extremes—laughing so hard he threatens to choke on his joy, sobbing like the pain won't ever stop, raging as if he might just cause the end of the world. It's as if the gentle calm he constantly uses to soothe Regulus with drives him nearer to the edge of his own capabilities every time, pushes him closer to falling apart. 

And Regulus knows that knocking right now will turn out to be just another push towards that edge, knows that a fall from it might just kill them both, but he is lonely and weak and shaking and in pain, so much of it—so of course, he knocks anyway.

The music stops. The door opens.

Sirius does get mad.

But he conceals it well; rearranges his face a split second after it falls upon taking in his beaten little brother, then pulls Regulus into his arms without further questioning. He wipes at his tears and presses a kiss to his forehead, puts him into his bed and recounts monster-less stories until Regulus has fallen asleep—and then he slips out of his room on quiet feet to scream at their parents with all the pent-up frustration of a frightened eight-year old because Sirius was always too close to exploding when it came to Regulus.

His wrist is broken, the next morning. 

He fell down the stairs, he says. 

They both know it's a lie, but as they stare at each other, tired and bruised and desperate and broken, neither has the energy to point it out. For the first time, the brothers don't have anything to say to each other.

There's no breakfast waiting for them, and Regulus knows that there will be no lunch either. Dinner, maybe, if they manage to stay sufficiently quiet during the day—which, judging by Sirius' set jaw, probably won't be the case.

At noon, their mother shakes her head at Regulus in something akin to disappointment—as if this is his fault; and now he is starting to think that it might be—then sighs when she finally inspects her eldest son's arm. It's a collection of colours, blue bleeding into purple bleeding into black, swollen and distorted and painful and Regulus' fault because he failed at protecting him and oh god, why couldn't he just keep quiet? 

There are tears in Sirius' eyes. He keeps blinking them away in defiance, locks his jaw as cold fingers prod the newest damage they inflicted, holds his breath as he awaits his verdict. 

"Orion," their mother says simply, another sigh escaping her lips as she lets go of Sirius' arm in dismissal, and Regulus wants to scream in all the ways he needs to be quiet.

She sends them off to the hospital with their father, fifteen hours after the fall. Regulus has to stay in the car—because two bruised children might raise too much suspicion—and when Sirius rejoins him on the backseat, he is proudly showing off his new bright red cast as if this was worth it. 

It's not.

And it's not the last time Sirius will try to lay hands on their parents in retaliation, but it was the last time Regulus found himself in front of his brother's door with tears in his eyes and a silent plea for comfort on the tip of his tongue.

Maybe it won't come to this again if he just behaves. If he does as he is told, if he stops talking back, if he learns to swallow down his cries, if he lowers his head some more. If Regulus needs to be a better son in order to become a better brother, he can do that. 

He can be better, he thinks, six years old and trying, his forehead pulled into a frown as he watches his brother take his dosage of pain medication in the evening.

He can be good. He has to be.

***

When Regulus is nine years old, the virus breaks out, and no one is prepared for it. 

It's just a vague threat at first, a whole lot of nothing to worry about just yet that quickly turns into thousands of deaths over the next few weeks—and suddenly there is something to worry about. 

"What does airborne mean?" Regulus asks quietly, lips moving against the shell of Sirius' ear as twin pairs of blue eyes stay locked onto a concerned-looking news reporter.

"It means we're in trouble," his brother whispers back, and for the first time in his life, Sirius looks scared. 

He looks considerably less scared and noticeably more excited once the schools close three days later, then huffs in annoyance once he realises it just means more homework. Workplaces close, then stores, then roads, then whatever was left after that, too. Windows stay locked and so do doors, days stretch into weeks, hopes rise then fall, then get buried as death lurks outside their houses, in more forms than one. 

The news reporter dies. The new one wears a mask and an uncomfortable expression as he recounts the same things his predecessor did. The lockdown goes on, the virus keeps spreading, people keep dying—or turning into something far worse.

It's been three decades since the solar storms, and humanity still hasn't managed to figure out how to stop itself from dying out. 

Regulus, currently nursing several new bruises from his latest disagreement with his mother and suffering from a spectacular headache because Sirius is going through a phase that involves listening to music on a volume that should be considered illegal, thinks that maybe humanity should just take the easy way out and be fucking done with it. 

From the bottom of the staircase, their mother screams at Sirius to turn off his music. From inside his room, Sirius dials his beloved screaming up even higher. 

From under his blanket, Regulus groans. 

The downside of being forced to stay at home is exactly that. It would be fine without their parents here, he thinks—but all of them locked into a house that feels decidedly too small for everyone's temper, it's been...unkind, to say the least.

Absentmindedly, he picks at a scabbed over cut on his upper arm and wonders why the hell Sirius can't just do as he's told for once. They're going to have to eat kale for dinner again if he keeps this up; and while Sirius will smile triumphantly down at his plate as if it's some kind of award for being ridiculous, Regulus will have to fight the urge to throw up. He hates kale.

"Just turn it off!" he yells, poking his head out from under his blanket and half-turning towards the general direction of Sirius' room. 

It's his fourth radio already. Regulus has no idea where he keeps getting new ones whenever their mother smashes the current one into tiny pieces. He's intrigued, but not intrigued enough to give in and ask to be included in the kind of silly secrets that once used to belong to both of them.

"Stop yelling!" their mother demands, her voice a little clearer and a lot more angry. 

She's coming up the stairs in that quiet, composed way that means bad trouble, and Regulus hurries to get out of his room. The blanket catches on his legs; he falls, curses, then crawls to the door, knees aching, heart thundering in his chest. 

"Stop telling him what to do!" Sirius bellows, throwing his door open at the same time as Regulus peaks through his. 

He's been doing less of that lately, protecting Regulus as if it's the only thing he can do, but he hasn't quite managed to stop just yet. And even though Regulus berates him for it, snarls and complains and ignores him to show just how little he thinks of the whole thing, a part of him hopes Sirius will never stop to look out for him. 

It's difficult, to slowly grow up. Regulus keeps trying to disentangle himself from his brother, but years of pain have knotted them too closely together. He's not sure where he begins sometimes, or if he even does. Maybe he's just an extension of Sirius, leftover parts that trail after him, cursed to stay in his shadow for forever.

He wonders sometimes, what exactly their parents see when they deign to look at him. The second born, the weaker link, the single means to control their wayward first son.

He suspects the first two, but is wholly certain about the last one—given that their mother reaches for him as soon as she appears on top of the stair landing, eyes narrowed and fixed on Sirius, whose defiant expression falters just a little as his gaze flicks to where Walburga's nails leave freshly bleeding scratches on Regulus' shoulder. 

Regulus doesn't look towards his brother. He hates to see how quickly the fight leaves his growing body whenever Regulus is added into the equation. 

"Turn off the music," Walburga says, awfully calm. She pushes at Regulus' shoulder, doesn't even watch as he stumbles a few steps towards the top of the stairs.

Her grip tightens. In his periphery, Regulus sees Sirius swallow. 

"Let him go first," Sirius orders, because sometimes she still pushes afterwards, just to keep the upper hand. 

"This is not a negotiation," their mother snaps.

There are more words, loud and angry and lost to the static in Regulus' ears as he forces himself not to shake. He bottles up his fear, forces his humiliation down towards the dread he keeps low in his stomach, and accidentally glances at Sirius, who always makes everything better. Maybe he really isn't his own person.

Sirius' eyes are already on him, not expectant, not even questioning. Just calculating, and sharp with anger. 

Regulus shakes his head. The movement is barely noticeable, but it doesn't need to be; not for Sirius, who catches his tiniest gestures, who is attuned to him in ways no one else ever bothered to learn. 

It does the job. And Regulus hates himself for it, but he hates the stairs even more. They always hurt the most. He never managed to figure out how to roll his body to protect it from harm. It's hard, in this house, and Sirius knows it perfectly well, too.  

Help me, he begs, and of course, Sirius does. 

He looks desperate when he whirls around, then furious when he stomps back out of his room with the radio in his hands. Blood rushes through Regulus' ears, rivalling the sound of static now. He's not even sure if he is breathing—but he definitely stops breathing when Sirius throws his radio down at their mother's feet with the kind of frustration that comes from years and years of hurting for two. It shatters, and so does the old wooden floor beneath it. 

Numbly, Regulus watches metallic pieces roll down the landing. They'll have to be careful with splinters later, he thinks. 

"Are you happy now?" Sirius demands, voice loud and angry as he steps right in front of Walburga, fists only uncurling to push Regulus out of her reach. 

He goes easily. It's a choreography at this point. Take three steps, look at the floor, listen to a palm landing on a cheek. Drown out the sounds of two quarrelling voices that match each other in fire but never in gentleness, feel guilty for being the odd one out, in more ways than one. It's a dance he can't stop himself from participating in, every movement bringing him right to the brim of paralysis. 

"Happy?" Walburga scoffs, her tone cruel. "With the two of you in my house?"

Voices rise as Regulus' heart continues to sink, the static won't leave, his body feels foreign, his lower lip wobbles treacherously—and then there's movement, and a hand on his arm.

He flinches, and so does Sirius.

"Just me," his brother says quietly. 

He sounds upset, looks like it too, and Regulus tries to ignore the red imprint on his cheek, the hint of blood left behind by nails in a matter that is calculated and learned, not accidental, but fails immediately. It's been years, but he still hasn't gotten used to the sight of it all.

When he was still a bit younger, Regulus used to wake up and cling to the brief belief that it was just a nightmare, only for his childish hopes to shatter like that set of plates Sirius threw around the first time Regulus sat down next to him with a bruise that covered almost half of his face. Every morning, it hurt to realise.

Nowadays, Regulus wakes up and just wishes he could go back to sleep. 

"You okay?" Sirius asks, as if Regulus is the one who's been hurt. 

Truthfully, it does feel that way, more often than not. He rubs his own hip where a bruise forms on Sirius', his skin pulls taut right where he knows his brother's has been forced to break apart, he lies awake at night sometimes, aching with scars that aren't just his own.

These wounds, this pain, this life; it's all theirs. They share it without choice and relief, but they do share it. 

He hates and loves it at once.

"It was just...," Regulus finally offers, looking away. "The stairs."

"I know," Sirius sighs, and he does, because he's got bruises and scars and a wrist that aches when the weather changes. Of course he knows. Most things, he knows better than Regulus. 

Warily, Sirius extends his hand towards Regulus. "Come on," he says softly, as if he's speaking to an easily spooked animal. "Didn't you have math homework?"

"I finished that already," Regulus mumbles, and even though he doesn't take his brother's offered hand, he holds the door open for him to slip into Regulus' room. 

While Sirius unceremoniously drops down onto Regulus' bed with a loud groan, curious fingers already reaching for the stack of dog-eared books on his bedside table, Regulus leans back against his door, taking a moment to collect himself before his brows draw together in disapproval. 

"Don't touch those," he says, merely causing Sirius to roll his eyes. 

"God forbid you have to share something," he mutters as he flips through the pages—but Regulus is sharing, all the goddamn time. His nightmares and his injuries, his food and his clothes and that small box of bandaids and bandages they keep in the upstairs bathroom to patch each other back together during the dead of the night, wary of the sound of running water, of swallowed-down whimpers, of creaking floorboards. He shares his tears and his laughter, the good moments and the bad hours, until everything becomes theirs and nothing feels like his anymore. 

He just wants a single thing for himself sometimes. 

"I mean it," Regulus insists. He tries to sound demanding, but his voice breaks halfway through the sentence and makes it sound more like a plea, a whine.

Sirius drops the book with a sigh, then rolls onto his back to glance at him, lower lip caught in between his teeth. He looks far older than eleven, Regulus thinks. Sirius always managed to look older than he really was. He straightens his shoulders, raises his chin, narrows his eyes, and sometimes Regulus forgets that they're almost the same age.

"Your radio's broken now," he states. He doesn't outright acknowledge why it is broken. He does, however, wonder why Sirius did it. 

Wonders if he smashed a thing so he wouldn't lay hand on a human, and wonders if Sirius ever thought about pushing their mother down those stairs. Because Regulus did. The second time she pushed Sirius down, he stared at her twisted expression during dinner and hoped it would have been her instead. Dreamt of it, too.

"I have another one in my wardrobe," Sirius drawls, obviously pleased by that fact. 

Regulus can't bring himself to ignore how his cheek is starting to turn a light purple. Once upon a time, they used to make games out of who could find more shades of colour in their bruises. Sirius always won. He always had way more than Regulus. 

"We'll wait until tomorrow to take it out," he decides now, lips pursing in thought, then curling up into a smile. "You even get to decide on the music." 

Regulus, unlike his brother, doesn't care all that much about music. It's one of the only things they actually fight about, so Regulus has committed the covers of Sirius' favourite albums to memory and points towards one of those whenever he is asked to choose nowadays. Sirius will tell him he's got amazing taste, and Regulus will nod, pleased despite the fact that he still prefers silence. It works just fine. It's one of his best tactics to gain his approval so far; he's rather proud of it—because he remembers all the covers of his least favourite albums too, which is excellent for when he wants to piss him off. 

"Where do you keep getting them from anyway?" Regulus questions eventually. It's not quite as casual as he initially planned for it to be, but Sirius is grinning when he eagerly sits up on his bed, clearly satisfied to finally have been asked, so it's fine.

"You remember that record store near the bus stop?" he asks, bright eyes fixed on Regulus, who slowly nods. Of course he remembers that. Sirius used to pull him over the threshold of said store at least four times a week when the schools were still open. 

"Gary, the owner, he offered to teach me how to fix up old hardware a few weeks ago. People drop off their broken stuff at his place, and if we manage to get it running again, I sometimes get to keep it." He grins down at his interlaced fingers, hair falling into his face. He's been growing out his curls lately. Regulus half-wonders if it's so he can hide the bruises from himself in the mirror. Ever since they started to stay home, it's gotten worse.

"I'm pretty good at it, you know?" He sounds proud, looks like he's expecting his brother to be impressed—but Regulus is just concerned. 

"We're not supposed to go outside anymore," he states, a little uncertain. 

In between two blinks, the tentative smile slides off of Sirius' face. He shakes his head, then lays back down onto the bed, uninjured side of his face turned into Regulus' pillow.

"It doesn't matter much, does it?" he mutters darkly. "This isn't much of a life anyway."

And Regulus. Regulus doesn't really have any kind of answer to that. 

"You better have that mess you made up there cleaned up before dinner, or else!" their mother yells up from downstairs, and while Sirius huffs in annoyance, Regulus grimaces. It's definitely going to be kale tonight.

"I have some cookies in my room," Sirius sighs, reading Regulus' irritated expression without needing more than a quick glance. It's an easy call; he's been eating Regulus' kale for more than six years.

"I'll help you clean up," Regulus offers. He's been trying to give back lately, but when his gaze catches on Sirius' freshly bruised cheek, he realises he's still got quite the way to go.

"You know what would actually help?" Sirius mutters as he gets up, trusting Regulus to follow him back out into the hallway. "If they'd just get sick and die."

And surprisingly, just a year later, they do.

***

Walburga and Orion Black die next to each other, right in front of the two boys they leave behind, on a warm September afternoon, inside the house they've been cooped up for the better part of sixteen months.

Regulus is ten years old, and not all that freaked out by the pair of dead bodies in front of him. 

They look like they're sleeping, he thinks, but he doesn't say it out loud, because they also look like their throats were slit, and there's no one around to listen to his pondering anyway. Sirius is upstairs, throwing clothes into bags. 

Regulus can hear him, if he concentrates hard enough. The frantic shuffling, the careless banging of doors and dressers, the not-so-quiet sniffing that accompanies his silent crying. 

Sirius isn't grieving—at least Regulus doesn't think so—but he is hurting. Regulus knows he is. He watched him crumble afterwards, knife slipping out of his fingers to clatter onto the floor. No one was around to scold him anymore, but Sirius still cowered in fear. 

It's a mystery to both of them how exactly their parents got sick. Not that it matters much now but...Regulus still wonders. If someone coughed into their direction when they were getting their monthly groceries from the distribution centre or if someone sneezed on the other side of the street when they went on a walk because they couldn't stand to be in the same house as their children all day. If they knew. If they had an earth-shattering moment of realisation, or if they just slowly lost that slim rest of humanity they carried in their rotten hearts. 

Regulus wonders, as he carefully closes the eyes whose gaze he craved and simultaneously tried to escape his entire life, if they saw it coming before it was too late. If they planned to take their boys down with them. 

Did they catch the way their veins slowly turned black and thought finally? Did they even try to fight the paranoia that snugly settled into their brains, that made their eyes twitch and their fingers tremble and their bodies turn into something dangerous?

Maybe the brothers could have caught it earlier, if they hadn't been so hellbent on avoiding their parents at all costs. Maybe then, it wouldn't have come to this. 

But then again, it doesn't quite matter anymore. It already happened; it's done.

Because Sirius' brows had drawn together in suspicion this morning when he woke to the sound of their mother's snarling, because he had sneaked downstairs, with Regulus in tow, to see her crouched on all four, muttering nonsense, with spit running down her chin and madness in her gaze. 

Sirius paled and Regulus' breath hitched and everything happened quite fast afterwards. 

He watched, wide-eyed and breathless, as Sirius knocked out both of their parents in a fight that didn't seem fair because it wasn't, because it was just a boy against two monsters—but it was a boy that could evade cruel hands easily because that's what he'd been trained for all his life, so he did what he was accidentally taught, and he did it well. 

"Look away, Reggie," Sirius said after, when hands and feet were bound and plans were made as they paced the floor, when a weapon was obtained, and a decision was made. 

There was fear and bravery fighting for the upper hand in Sirius' gaze, and he begged Regulus to turn, but Regulus did not.

He looked right at his brother as Sirius slit their parents' throats. First their father's, then their mother's, and then it was just them and two bodies, and somehow it still didn't feel as if anything had changed at all. 

Sirius came towards him slowly, holding up his hands. His eyes were so troubled when he croaked, "Don't be scared, alright? I—"

"I'm not scared of you," Regulus interrupted, expression bewildered as he scrambled up from his seat on the staircase to run to his brother, to bury himself in his arms, to hide his face against his chest. To breathe in the familiar smell of the one and only person Regulus never wanted to lose.

Because Regulus loved his parents, in that innocent way children can't save themselves from, but he loved that they didn't get to hurt them ever again even more.

"Now it's just us," he whispered into the soft fabric rubbing against his cheek. As if it ever hadn't been just them.

"Right until the very end," Sirius promised quietly, protectively circling his arms around him. 

And Regulus had believed him effortlessly—but it is him, in the end, who makes him break their promise.

***

Their entire life, they have dreamed about finally leaving behind their home, prison—house. It's an easy decision; as easily made as it is soon regretted. 

Life on the streets, as it turns out, is not all that easy. Especially when the world is ending. And in a way, the world has been ending for the brothers ever since they set foot into it—but this is different. 

When September morphs into October, the temperature drops. 

Two weeks later, Sirius gets sick. 

His veins don't turn black, but his skin turns red with fever, then grey with exhaustion. His limbs turn to lead and suddenly, Sirius can't walk the smallest distances. Days later, he can't even sit up anymore.

Regulus is scared out of his mind.

They take refuge in an abandoned house, towns away from the one they grew up in. The windows are smashed and the food is already stolen, the water is off and the heating won't turn on either—but it keeps the rain away from them, and the nights become bearable again. 

It's no home, but then again, neither was theirs. 

In the darkness, their arms are tightly pressed together, and while Sirius succumbs to fever dreams that leave him shaking, Regulus monitors his breathing for hours, half-expecting every hitch to be the last.

He is ten years old. Life has never been particularly kind to him, but it still decides to take a turn for the worse, just to test how much he can withstand.

They need medication and food, so Regulus fights with Sirius until he lets him go and get some. It's an ugly fight, too many sharp words that refuse to be held back by trembling lips, but Regulus isn't just going to let his brother die. He wants to wring Sirius' neck for even suggesting it. Wants to dig bitten nails into their clasped hands until they both bleed, wants to point at perfect droplets of crimson and yell, we're supposed to be the same.

All those matching bruises, all those dedicated smiles, all the times they wiped the blood that connects them from each other's tear-streaked cheeks after their parents summoned it in painful ways; Regulus refuses for it to mean nothing.

"You are not going to die," he bites out, and then he leaves to make sure of it, ignoring the weak complaints Sirius sends after him.

None of what he does afterwards was supposed to happen. 

It takes him an hour to get to the nearest store. The door is smashed to pieces, the light is off, the floor inside is dirty with dried blood and spilled, mouldy food—and Regulus hears the snarling waiting for him around the far corner of the healthcare isle just a tad too late. It's one of those things, those creatures that the news kept warning about before television stopped being a thing, those monsters that their parents tried to turn into, and suddenly, it's right in front of him, on all fours as it whirls around to growl at Regulus in warning. 

He still remembers the way humanity collectively held its breath when they slowly realised what the virus really meant. What it did. When the living turned into the dead but kept walking, and everyone gasped in disbelief, in shock, in unadulterated fright. Those weeks were the scariest, he remembers. That small window of uncertainty and fear, before half the population disregarded the lockdown and decided to flee, even though there was nowhere to go anymore.

He's seen those first shaky videos they released to the public; everyone has. Skeletal bodies with papery skin that barely managed to cover protruding bones. Twisted limbs and distorted faces, wide-open mouths and black teeth that dug hungrily into flesh. Blood running down pointed chins and crazed eyes fluttering closed in bliss while their victims screamed in agony at first, then stopped fighting a battle that couldn't be won and died, slowly and painfully. 

"Not a good death," Sirius had surmised back then, his face a picture of discomfort—and Regulus is glad that it's only him now, who has to face the possibility of it. That Sirius is safe, relatively at least. 

Regulus isn't scared; he just wishes he could still take back some of those things he yelled earlier. Just in case. But he can't, of course, so he'll just have to make it back to his brother's side, no matter the cost. 

Fix this, and everything.

Briefly, Regulus wonders who the thing in front of him was before. If the man it used to be once had a family to fight for, or dreams that occupied his thoughts even outside of sleep. If he'd been aware of what it meant when his veins first darkened with sickness. If he was scared. Or alone. Or both.

Briefly, he wonders. But then the knife Sirius told him to start carrying appears in his hand like it always belonged there and minutes later, he has learned how to take a life with it. 

He's not just defending himself; he is defending Sirius, too. And he is fine, because he watched Sirius very carefully when he moved that knife over their parents' throats all those weeks ago, and there might be blood on Regulus' clothes afterwards, but there is medication securely wrapped in his arms too, and that's more important than the sick feeling to his stomach, or the way his hands won't stop shaking now.

He cleans his knife, finds some food, carries as much of anything as he can, and leaves without looking back.

"Are you hurt?" Sirius mumbles through a haze when Regulus appears back by his side. Weakly, his fingers move up to scratch the spatters of dried blood off his collarbone. 

"No," Regulus mutters, swatting at his hands as he rips open a blister of antipyretics. He threw up on the side of the road earlier, but at least his fingers stopped shaking afterwards.

"You're bleeding, Reggie," Sirius insists, trying to sit up now, with new fear in his eyes. His breathing quickens, and his movements are all off, and Regulus pushes him back down again with a little too much force, fisting his shirt on instinct. 

"It's not mine," he says simply.

"Oh," Sirius breathes, relief imminent in his voice before the implication of his words fully catches up to him. His eyes widen, then fill with tears. "Oh, Reggie." 

"It's fine," Regulus says, and his voice is not choked because it is fine. They are brothers, and they are killers. 

They are the same.

Except that they aren't—because despite the medication, Sirius doesn't get better.

He gets worse instead. 

It was his birthday last week, and Regulus is frightened by the possibility that he might not get to see another one. The winters are cold, even after the solar storms. Not quite as icy as they used to be, but too much to handle for a pair of struggling lungs. 

It's only November, and Sirius is all rattling coughs now, grows thinner and thinner as he sleeps away the days they spend huddled close together in their little house, wakes up disorientated from fever dreams and needs more time to tether himself back into the present every morning. 

He tenses and shudders and shakes and cries, and every night, Regulus thinks he will lose him. 

"I'll keep you safe," he tells his brother as he figures out a way to heave him up onto his back and starts carrying him towards what might be left of civilisation elsewhere, pausing only to catch his breath or to shield Sirius from the never-ending rain. The low light of the stars casts sorrowful shadows over both their tear-streaked faces, and Regulus knows it's bad because Sirius doesn't even fight him. He is quiet and boneless, lets himself be carried and fought for, and Regulus begs and prays and pleads that he will hold on just a little longer because wherever Sirius goes, he will follow. Even into the afterlife.

If there is one.

***

Regulus doesn't know if it's a mere coincidence or a sudden generosity of destiny, but his fate is sealed either way when he meets Albus Dumbledore.

It's laughable, really. Or almost, at least.

Dumbledore, unlike him, is not walking alone when they first meet—because only stupid boys wander the streets solely by themselves in times like this; stupid boys that become orphans in their homes and murderers in abandoned grocery stores and only children in the depth of winter when their brothers inevitably die right under their freezing hands—but he is signalling his companions to stay back as he slowly approaches Regulus, as he begins the kind of story Regulus will forever hate telling. 

His steps are short and measured, his hands raised as if Regulus is more of a scared animal and less of a starving boy—but his smile is blinding, his teeth bared as if to mask the curiosity in his expression, the hunger in his eyes. 

Regulus doesn't trust him at all, but Dumbledore isn't asking him for trust. Not yet.

"Look at you," he says, and there is the kind of wonder in his tone that Regulus only ever remembers having heard from a younger Sirius, back when having a sibling was still a novelty to him. "You must be cold, son."

Through narrowed eyes, Regulus watches the man shrug out of his winter coat, uncovering a slim but strong build. He's got brown hair, slicked back to reveal sharp features and kind eyes, a growing beard, and the offer of warmth in his outstretched hands.

Regulus takes the coat. He might be wary, but he's not stupid. 

Pleased, the man nods at him. He steps a little closer while Regulus throws the thick fabric over his shoulders, until he stands right in front of him, as close as no other human being has gotten to him in months. Except Sirius. But Sirius doesn't count.

"Where are your parents?" he asks, searching Regulus' expression. 

"My brother is sick," is what Regulus replies with. When the man's expression turns from curious to regretful and solemn, he quickly adds, "No. Not like that." He's breathless with the possibility, shaken by the mere idea of it. "He's got a cough, and a fever."

He's had both for quite some time. Though Regulus doesn't say that out loud.

Glancing back over his shoulder, the man nods some more. 

An argument of glances and cut-off gestures erupts, and Regulus, who grew up practicing that very same kind of silent conversation with Sirius in a house that was often too quiet for actual words, finds some strange comfort in watching the group of strangers communicate through measures he thought of as his own.

Maybe they can help, he thinks—but he doesn't ask for it. He's ten years old, and he has already learned that help has to be offered, not requested. 

So he waits, with the kind of patience he doesn't feel. Shrugs a little deeper into the soft material of a stranger's coat, raises his shoulders until he looks younger, widens his eyes until he looks a little more scared. He waits and he watches, and eventually, when half a dozen pairs of eyes linger on his freezing form and soften with pity, he thinks, thank god, even as it makes his skin crawl. 

"Show me your arms first," he demands, once they reach a silent conclusion, once they ask him where his brother is, once they use gentle voices and sympathetic smiles, once Regulus understands that they don't really expect to end their day with having saved two boys, but that they're keen on saving at least one. 

His shoulders drop again, his eyes narrow. He makes sure to harden his voice, hopes it sounds a little more like Sirius'. Assertive, sure, like he knows what he's doing here. 

The answering smile of the man in front of him is gentle but clearly amused. "None of us carry the virus," he says. "You don't need to worry about that."

"Good," Regulus acknowledges. "So you won't mind showing me your arms. All of you." 

His world begins and ends with his brother, and he is not taking any chances. They might want to save him, but Regulus isn't interested in life if fate decides to pull Sirius in the opposite direction—and he thinks he makes that quite clear right then and there, or at least clear enough. 

His back is squared so he appears taller than he actually is, his chin points high up. The jacket covering him conceals just how malnourished he has become, but it's still light outside, so nothing quite manages to hide the desperate frenzy that entered his gaze back when he slid a knife across another being's throat and found out the sound of collapsing airways. It's fine, but it haunts him. There was blood on his hands afterwards, so much of it.

He still has that knife. 

For a moment, he thinks about reaching for it.

But they are staring at him, curious and calculating, and he is staring back, determined and wary—and right before he loses his mind, a woman shrugs out of her jacket, pulls up her sleeves, and presents her forearms to him, free of any signs of infection. Her brown hair is short and slightly curled, her thin face seems aged, and her voice is quiet when she tells him, "You are very brave," but it carries nonetheless. There's something akin to admiration in her tone that causes Regulus to blink. 

A moment later, he wordlessly turns towards the next pair of arms presented to him. 

He doesn't feel brave. He never has. 

As soon as they get back to Sirius, Regulus shrugs out of his newly acquired coat. He drapes it over his brother's shivering form long before any of the adults cautiously trailing behind manage to set foot into the small shed he chose as their newest refuge last night, when his arms and legs threatened to give out and Sirius' wet coughs threatened to wake more than just the dead.

"I found help," he tells Sirius, a hushed whisper of excited tension that meets unhearing ears because Sirius won't wake, refuses to find his way back to consciousness, just moans in his sleep, pained and afraid. 

Regulus isn't surprised. He's been like this for almost two days.

But it becomes rather clear, when the cautious shuffling behind him morphs into alarmed glances and raised voices, when questions are asked and permission is granted, when hands reach for thin limbs and tall shapes hurry to bring both of the brothers elsewhere, that the strangers didn't really expect to find a second boy. Much less an alive one.  

After, they rush through abandoned streets. By foot at first, then in a car. The heating is on, which seems like a novelty—but Regulus still feels so cold, with Sirius' head in his lap, his life in his hands, his fears in his throat.

Pneumonia, they say when the scene changes again, when streets are exchanged for a familiar set of bright walls and long corridors and a sinking feeling in his gut. 

Beginning respiratory failure. The possibility of sepsis. Complications that try to eat his brother alive, complications that almost succeeded in eating his brother alive. His immune system is failing him, they say. Working against him now, exhausted by too much stress, too much strain, just too much.

At some point, Regulus sinks into a chair. No one forces him to get up. They pat his shoulder, smile. Use gentle voices to tell him that they can fix all of it easily, that it is nothing science hasn't already solved decades ago. It's nothing like that virus out there, they whisper to him in hushed voices and conspiring tones as they let their palms linger on his drawn-up shoulders. That one, they swear, Sirius would not survive. So they shouldn't leave, they urge. They should stay instead, for a few weeks at least. They can fix him, they promise.

If Regulus agrees to help. 

He is ten years old. His gaze is locked onto Sirius, on his pale skin, on his closed eyes, on the gentle rise and fall of his chest, caused not by his own breathing but by the ventilator he is hooked up on. He's in an actual bed. Has stopped shaking for the first time in weeks. 

They can fix him.

It's not really a question. 

He says yes either way.

***

Life at the facility—Crucio, they call it—is better than on the streets; for Regulus at least. 

Immunity, they whisper one day, awed and fascinated and hopeful as they gently remind him of his promise, and how could Regulus not act on it now? Of course he wants to help. Of course he wants to do as they say. 

So he does exactly that.

He feels...important, suddenly. Needed in ways that go beyond his and Sirius' half-hearted scheming in order to avoid falling victims to their parents' hands. And he's still too young to figure out that it's a bad thing, but that's not his fault. Not really.

They treat the brothers well for the first few weeks, and Regulus almost can't believe that such kindness exists. He eats and sleeps and stops to feel so scared out of his mind. He listens to other people's hushed conversations and tries to hold eye contact when they turn their questions onto him. He nods and thinks and replies; learns to hide his flinches at quick movements, learns to read calculations he's never seen before at school, learns to trust, as well as someone like him can learn to do that. 

Sirius, however.

Sirius does not trust, nor does he want to. He grows quiet, reserved, then impatient. Refuses to say much to anyone but Regulus, and only ever uses his voice to wield complaints and start arguments. 

"We should leave," he says one day, all thin limbs and wariness as he fidgets on top of the infirmary bed they still keep him in. He's glaring, too—not at Regulus, but at the small camera in the corner of his room. 

"We can't," Regulus mumbles back, careful to speak quietly. "Not when you're still sick." He's instinctively echoing Dumbledore's exact words—because of course Regulus brought it up to him already, because of course he anticipates Sirius' wants before his brother has even voiced them—and although Sirius may not know that, he scowls in displeasure either way. 

Regulus changes the topic. Sirius lets him. It goes on like this for quite a while.

Weeks pass, then months. They start doing tests on both brothers, harmless ones at first, then ones that seem a little questionable, too. 

"We simply want to understand that special brain of yours," Dumbledore reassures him with a smile, his index finger playfully tapping Regulus' temple. "You know how important it is for us to understand your immunity, what it could mean—don't you, my boy?" 

"Of course," Regulus agrees, but he's frowning and reconsidering and wondering. Not because he doesn't understand the collective need for a cure against something so horrible—he does, and he wants to help if he can—but because Sirius won't get better, and Regulus can't figure out why.

"It's to be expected," the doctor tells him when Regulus keeps asking, almost daily now. She's got kind eyes and fancy words in store for him, and Regulus nods at her, even though he doesn't feel particularly convinced, or reassured. 

He's standing outside of Sirius' door, arms crossed in front of his chest. Again, his shoulders are squared and his chin is held high—but his eyes still fill with tears when the doctor finishes a long line of lies with the assurance of Sirius' continuous improvement and leaves.

Regulus' shoulders fall just a second before the rest of his body follows. He sinks down onto the floor, pulls his knees tightly against his chest, hides his face and his fear and the uneven staccato of his breathing because Sirius is asleep and in pain, and Regulus is out of his mind and out of his depth—and there's a girl in front of him suddenly, crouching down to meet his teary-eyed gaze when he blinks at her in confusion. 

"Oh dear, are you alright?" she asks, frowning before Regulus can, then interrupting both of them. "Wait, no. That's obviously a stupid thing to ask—don't answer that. Here."

Almost violently, she rips a tissue out of her back pocket to present it to him with a tentative smile—and Regulus only takes the damned thing because he's feeling a little overtaken by surprise, but the girl nods in approval either way. 

She can't be much older than sixteen, he thinks—but he hasn't been around other kids in so long, he can't be entirely sure. Lately, he feels like he knows less and less, feels like it's all slipping away from him. He studies her dainty features cautiously—the pale complexion, the hooded eyes, the short bob of hair, so bright under the overhead light that it appears almost white—and let's her do the same. Wonders what she sees, and if there's anything to see at all. 

Her gaze skips all over his face, like a hummingbird that wasn't made to settle. A second later, she cocks her head, quirks her lips up into a shy smile, and says, "You're quite young to be the saviour of the world." 

Regulus does finally frown then, appalled for more reasons than one. The tissue falls out of his hand. For some reason, he picks it back up. "I'm eleven."

A pair of thin eyebrows rises in response. She looks...unimpressed. "Eleven? Are you sure?"

"'Course I am," he mutters, wiping at his cheeks with the back of his hand. "It was my birthday last week."

"Your birthday?" The girl's lips part around a soft breath of surprise, and her expression changes from disbelieving to heartbroken. "But where was the party?"

Glancing away, Regulus shrugs. It had been him and Sirius, in the same way that it had been him and Sirius for the other ten birthdays of his life, too. He doesn't mind. Doesn't know anything else.

"Well, we can't have that," the girl decides, straightening up to full height—which isn't all that much, honestly. "We've got to find you some happy-belated-birthday cake, at least." She holds out her hand, bites her lip, switches her weight from one leg to the other and back, and now it's Regulus' time to be unimpressed.

"That's not a thing." He narrows his eyes at her.

She just smiles. 

And Regulus must be losing his mind, because he might not take her hand, but he does get up. And his knees ache and his head throbs and the world seems a little unsteady all of a sudden, but he tentatively takes a step away from Sirius' room in the infirmary, and hates himself for the fact that he can immediately breathe a little easier.

He hesitates, his eyes flicking back and forth between the door behind him and the stranger in front of him, his flight slowed down by hot guilt. He shouldn't. But— 

"Can we get some for my brother, too?"

"Sure we can," the girl says seriously, and it's a done deal. Regulus starts walking, a bit too fast, too desperate, too ashamed, but she just follows him, her voice soft with understanding when she asks, "What kind does he like?"

This is insane. He is insane. "Chocolate." 

They're supposed to stay together, to watch out for another, to protect each other. That's what brothers do. 

"A classic." She nods as they casually fall into step side by side, as if it's nothing—but Regulus feels physically incapable to stop walking. He is still clutching her tissue, unsure what to do with it. What the hell is he running from here? The blood on his hands? His brother?

"And you?"

He flinches, then remembers the conversation and shrugs. Can't quite explain that he couldn't care less about some stupid cake flavour when he suspects to be losing his mind. He thinks watching Sirius fail to get better might end up driving him straight to insanity—but then he thinks about the smile that some cake might be able to put on Sirius' face, and how he's been smiling less and less, those past few weeks. This is good. An excuse for him to keep fleeing, just for today. 

"What's your name?" he asks, blinking his thoughts away. If the girl minds the sudden change of topic, she doesn't show it.

"Narcissa," she says easily. Regulus hopes she knows where they are going, because he's got no clue.

"Like the flower?"

She pauses there, as if Regulus somehow managed to take her by surprise. Her gaze settles on him, then flicks away again. "Exactly like the flower, yes."

He hums in acknowledgment, dodges a group of people walking past them. With every step, breathing comes a little easier. Finding words does, too. "I'm named after a star."

"A star, huh? My sister is, too. Bella." 

Curious, Regulus side-eyes her. He doesn't know a star named Bella, but he kindly decides not to point that out. 

"You've got a sister?" he asks instead. 

"Two actually." Narcissa laughs, though she doesn't sound all that amused. "I'm the youngest."

Almost against his will, Regulus lights up. "That's—Are they here, too?"

"Well. They're...around." 

"Oh." His spirit dampens again, like an endless cycle. "They're not sick, are they? My—My brother is."

The small smile Narcissa throws him is a gentle one, almost apologetic. "So I've heard. Let's see if we can get him back up on his feet with the best chocolate cake of his life." She nods towards the elevator coming into view, then lowers her voice conspicuously. "Lucky for you, my sister entrusted me with a secret family recipe that will forever cure your indecisiveness on cake flavours. You'll dream of chocolate cake afterwards, little star."

There's a laugh caught in the back of Regulus' throat. To swallow it back down feels almost impossible—so he doesn't, and it blooms free like he hasn't in a long while.

"Is it from the one named after a star?" he asks later, his curious gaze taking in a kitchen he hasn't seen before—which isn't much of a wonder, given that he takes his meals either by Sirius' bedside or in Dumbledore's office. "Bella?"

"No," Narcissa mumbles. She looks away as she rummages through the cupboards, hides the way her smile has dropped expertly. "The other one." 

And Regulus has forced enough conversations to wilt and shrivel in order to understand perfectly well when to drop something, so they leave it at that.

They spend all day in the kitchen—and Narcissa was right about her family recipe, it is good, just not quite good enough to replace the nightmares that haunt Regulus' sleep. It's okay though; he didn't expect it to be.

They burn the first cake and declare it collateral damage. The second, they eat solely by themselves, straight out of the oven, giggling as they burn their gums and tongues and fingertips. But the third cake—their best one yet—Regulus brings back to Sirius, who sits up with red-rimmed eyes, and laughs for the first time in a week. It's a bit of a hollow sound, half-surprise and half-cough, but Regulus was right; his happiness tastes even better than the cake itself. 

It doesn't fix anything though. Sirius stays sick, Regulus stays by his side where he belongs, and the world keeps ending.

***

The attention on them wanes, after a bit. They were the first, yes; but they aren't the last immune children brought to Crucio—by far. They come sparsely at first, then in groups, almost weekly. 

Sirius asks wordless questions with the deepening crease in between his brows while Regulus pretends that the answers he suspects to be behind all of this don't keep him up at night. In a daze, he walks back and forth between the infirmary that houses his brother and the labs that test and teach him at once. Tries to tell himself that the new values coming in every day are just that, numbers instead of lives, and clings to the vague hope of a cure as he watches Dumbledore collect children like trophies. 

In the beginning, Narcissa still greets them with warm chocolate cake and calming words, but she stops once they start to stumble in in groups, frightened and crying, with blood splattered onto their clothes and tears clinging to their eyelashes, the sobs falling from their trembling lips the only thing left of the families they were forced to leave behind.

She looks haunted. Regulus looks away. 

It's far too easy, and it goes on for far too long. 

There's too many kids, so Dumbledore finds them teachers, throws them into classes, builds his own little school. Has them study history and mathematics in the mornings before in the afternoons, scientists study their brains in return, adding more and more variables to calculations no one really understands either way.

Until suddenly, they do. 

Until suddenly, they find the thing that connects all those wondrous children refusing to bow to the virus that has already executed a fourth of humanity. 

It's Regulus who stumbles upon the enzyme that tames the virus—and truthfully, it had been more luck than knowledge, but people tend to care very little about the how as long as the result gets them closer towards their goals, and this one does. Oh, how it does.

Their first answer in a long row of questions—and it comes with loud cheers and relieved sighs and squeezing hands on Regulus' tentatively squared shoulders. The change in the air is palpable, everyone's grip onto hope renewed, restored—especially Regulus' when, like clockwork, Sirius' condition finally improves. He's pale but walking, coughing less and smiling more, and Regulus doesn't even care about all those new tests that are ordered that very same night, and how they are getting more and more invasive, dangerous, desperate. 

He doesn't know any of these children; but he does know Sirius.

"Keep up the good work, son," Dumbledore tells him later, an edge to his tone that Regulus notices but can't quite place. It's so late that it's early again, and he is bleary-eyed and feeling oddly accomplished for something that had everything to do with chance and nothing with skill, but there's not much that could dampen his mood. Sirius is fine. 

Keep up the good work, he thinks, almost a little haughtily—and he does. Of course he does.

Just...maybe a little too well.

***

At thirteen, Regulus creates something horrible. 

And maybe he didn't mean to, maybe he didn't fully understand all the implications of his words, didn't quite grasp all the consequences of his actions—but he can't take it back now. 

That's the thing about choices. Even carelessly made, they ripple with an ocean of consequences, ready to be unleashed. 

"Why can't we just fight against a virus for which we actually can create a cure?" he mutters. 

The good mood didn't last. He's tired and overworked now, feels testy and pointless, doesn't even understand what he is doing here, inside those labs, so far from all the other kids. Back then, in those very first weeks, he thought he'd join their classes—or at least their daily experiments—but even before the enzyme discovery, Dumbledore had just gently shook his head and led him back to work, trusting in something that Regulus now fears to be proving wrong. 

It was a short-lived victory, the enzyme. It can't be extracted, or duplicated, or fully figured out. All of the immune carry it, but not in the same amount—and even that keeps changing on individual levels, depending on factors no one at Crucio seems to agree on, and Regulus just doesn't understand. Hence the bad mood.

Next to him, Narcissa releases a quiet laugh at his words. Her eye-roll is more due to exhaustion than actual criticism, but Regulus is only half-aware of it either way; his eyes are on Dumbledore, whose gaze has inexplicably sharpened. 

"Elaborate, please," he says evenly, fingers gently thrumming on the table in between them. 

He does that sometimes, treat stupid comments as if they are really smart ideas, and while some years ago, Regulus had felt flattered, it grates on his nerves nowadays. 

"Well," he spits out, jaw working in frustration as he pushes away an empty mug of tea, "maybe we should just invent some new virus that we can control. Maybe they'll cancel each other out, or... I don't know." 

Put an end to this stupid farce, maybe, he adds silently. 

It's been years of research, at this point—though judging by what little they know, it seems more like weeks. They've been turning in circles while the earth threatens to stop turning altogether, half-emptied of its residents and struggling to regenerate on its own. And even though Regulus doesn't necessarily think that giving up would be the best approach to this hell, deep inside, he fears that it's the only one left, realistically. They're just grasping straws, holding on to sharp edges in order to slow a downwards slide that cannot be stopped, not really.

"That's rather...," Narcissa starts with a frown, trailing off when she glances at Dumbledore. 

The older man is sitting up a little straighter now, his tapping fingers suspended in the air above the table, caught mid-movement. When he cocks his head, something shifts. Something fundamental.

"Hold that thought," he says, and for the next few years, Regulus will wish he hadn't.

They come up with it together, in the end. 

"Well, we know it's not about gender," Ariana states, somehow managing to pace the room while simultaneously staying close to her older brother. Dumbledore watches her out of the corner of his eye, tuned in to her movements in a way that reminds Regulus of himself and Sirius, oddly enough.

His eyes are still flicking back and forth between the siblings when he hums noncommittally. "Or about any genetic markers, really." 

"It had something to do with our tests though, didn't it?" Tom adds, noticeably gifted at inserting himself into conversations that started without him and would have honestly continued on that way just fine, too. He's been a recent addition to their research team, not yet lacking the eagerness that has long since been drained out of the overtired minds of the others, and is currently throwing Slughorn a loaded look of false importance. Regulus doesn't like him. 

Slughorn, better at dealing with chemicals than with people, barely manages to hide his wince over being addressed and visibly scrambles for a fitting reply. To his credit, he doesn't seem particularly enamoured with Tom either. 

"Indeed, yes." He clears his throat. "Particularly those experiments that initiated stressful situations were rather—"

Impatiently, Dumbledore cuts him off. "We've been over the correlation between cortisol and our immunity enzyme. What we need to focus on now is how to use that."

"Any suggestions?" McGonagall asks, her eyebrows slightly raised. Regulus glances at her, remembers the way she'd been the first to step forwards all those years ago, how she pulled up her sleeves and presented her forearms to him with gentle understanding in her eyes and quiet reassurances on her lips, and quickly glances away again. 

"We...stress them?" Slughorn proposes, sounding unconvinced. He scratches the back of his head.

"How?" Ariana asks, right as Regulus tiredly thinks, who even is them?

The thought wakes him up all at once. His heart starts pounding.

Because he is immune too, isn't he? Standing on that stark line between us and them, wondering where he will land when push comes to shove—because he will land somewhere. This won't go on forever. It can't.

He is thirteen years old, and he never really thought about it like that before. But maybe he should have.

Visibly eager, Tom leans forward. "If we could tweak the current experiments to—"

"No." With a click of his tongue, Dumbledore shakes his head. "It's no use; they know that there's no need for actual fear here. We won't hurt them"—he considers Tom, his eyebrows drawn together—"and we don't need to, either."

But do we want to? Regulus thinks, a little desperately. Do they? 

There's a clear distinction here, he thinks. It's in the way Dumbledore won't meet his eye anymore, too focused on the people who make actual progress because they aren't thirteen year old boys depending on luck and working on despair. 

"What are you saying?" Druella, Narcissa's mother, related more by blood than appearance, questions hesitantly. Regulus wonders whether she's equally confused about the whole us-and-them thing and thinks she might be. Her youngest daughter—not the one named after the star but the one Narcissa won't talk about—belongs to them, takes part in their classes and tests, shares their hope and pain and burden. Narcissa told him that at least, after weeks of kinship.

"We're saying that the levels of stress and fear necessary for the increased production of the immunity enzyme can't possibly be induced within these walls anymore," Ariana explains, voice oddly even. Regulus' ears ring. He can barely hear any of them. 

What is Sirius? Us, them, something else? Because he is everything to Regulus, but to Crucio, he is—

"So...we take them elsewhere?" Slughorn asks. "But what's out there that will stress them?"

To them, he is nothing. They both are, really.

And it's only now, that Dumbledore finally looks over at Regulus. He should have seen it coming, really. The glance, the smile, the beginning of an end. 

"A virus from which they aren't safe already, for example," he says. 

Regulus closes his eyes in defeat and denial and shame. The room is so quiet, his heart is so loud. He is thirteen and he doesn't even know these other kids but he is one of them too and how could he ever forget, and he is ten and protecting his brother and there is blood on his hands now and then and always. He never managed to wash it off. 

"That's...," someone starts. Horrible, demonic, terrifying, inhuman, wrong. 

"Inspiring," Tom finishes. He's smiling, and Regulus was wrong. He doesn't just not like him, he hates him. 

He glances all around the room, studies expressions as if it would still change something. Tom is nodding to himself, Slughorn is frowning, glancing at McGonagall, who has her lower lip in between her teeth as she works her jaw and stares at the wall behind Druella, both of them unmoving, lost in thought. Ariana has dropped into the chair next to her brother, expression somewhere between delight and apprehension as she mutters something under her breath, and Dumbledore....

Dumbledore is looking right back at him. 

"Regulus," he says softly. Not apologetic, because there's nothing to apologise for, not for him, and for once, Regulus knows exactly where this is going. 

For the first time in a long while, he is asked to leave the room. 

For a long while after, he does not get invited back in.

Us and them; and Regulus got his answers just fine.

***

He is fourteen, and there is a box of cake in his hands. It worked once, he thinks desperately, remembering Narcissa's hand and his own overwhelm and Sirius' smile. Maybe it can work again. 

Fittingly, he forgets about the damned cake as soon as he steps inside. 

It's not the first time he's seen James, but it's the first time he lets himself look. It's hard not to, really, when they end up barely centimetres apart, hands fitting together like puzzle pieces and gazes interlocked like magnets that refuse to part. He's staring, Regulus knows—but so is James, and maybe that's alright. Maybe—

"I'm James," he says, voice tentative and low and somehow oddly soft, and Regulus almost laughs, because he knows. Sirius hasn't managed to shut up about his new best friend ever since their very first game of cards seven months ago. It's all he ever talks about—and Regulus would be considerably more bothered by that fact if James' presence weren't so obviously causing Sirius an amount of joy and happiness he hasn't seen his brother experience in years. 

It's...complicated, he thinks. Even though he doesn't fully understand why.

"Regulus," he replies, fighting not to squirm under James' attention. He'd been careful to avoid him so far, partly because he never learned to share his brother and thereby isn't very good at it, and partly because he can't help but fear he might accidentally ruin their friendship in that way he ruins everything he touches. Us and them and everyone, and there's blood on his hands and dangerous ideas on his mind and sometimes he forgets but always he remembers—so he pulls back his hand with more force than strictly necessary and sucks in a desperate breath.

James is…still staring.

In a way, Regulus is used to it. Being stared at. He's always studied at Crucio, the centre of attention, the topic of conversation, the receiving end of dangerous questions and questionable projects and secret schemes. A few months ago, they let him back into that room, and a part of Regulus thinks he never really left afterwards. He doesn't feel like himself most of the time—but he does, right then and there. Under James' curious stare.

He's older, just a bit, and even though he hasn't been here for very long, he seems settled in ways Regulus feels detached, aimlessly floating through meaningless corridors that mean everything. He charmed Sirius' nurses in no time, handles his moods with ease and gentle care, reassures him, calms him, makes him smile effortlessly. Unlike Regulus, James doesn't need to come bearing chocolate cake to land himself in his brother's good graces.  

It doesn't sting, he tells himself—but even the best liars have their limits, and Regulus thinks James might be his. 

The cake is gone from his hands when Regulus snaps back into himself, and so is his brother, stumbling through the room, all pale skin and unsteady feet. It's a vicious cycle still, him getting better only to get worse. He's jumping around one week, then spends the next month in his bed, losing his weight and temper and mind. They change his pills, they run the same tests two dozen times, they say the exact same words from four years ago to Regulus, just in a slightly different order, and with no one left believing them. 

There are nagging thoughts on the back of Regulus' mind—but he forces them down, again and again, until he almost manages to forget about them. Because he remembers being ten years old, frightened that Sirius wouldn't see another birthday; and here he is at fourteen, watching his brother preen under the attention of people Regulus does not recognise, chocolate cake in his hands, then on his face, complimenting his wide smile. And it's got to count for something, Regulus thinks. 

He can ignore his stumbling when he focuses on the bright light in his eyes, can pretend not to notice the frail state of his body when he watches Sirius dance to off-key birthday songs. He can pretend that they don't constantly fight or lie or punish each other with silences because for once, Sirius keeps him close all night, whispering names and relations and secrets that aren't his to share into Regulus' eager ears. He doesn't care about gossip, but he cares to hear his brother's voice. 

He can pretend just fine; they both can. They grew up learning how. Hiding their injuries, their pain, their fears—just not from each other. That is new, and maybe the most painful thing of it all. 

It is reassuring though, to know that even through all the pretence they still know each other, understand each other, see each other. Because they do. Which is why it's not much of a surprise to Regulus when, hours after Sirius' energy started to wane enough for him to casually lean into Regulus' side for support, he suddenly clutches his stomach without warning, and throws up chocolate-cake-vomit all over the floor in front of them. 

When Regulus sighs, Sirius swats at him, affronted. "At least I didn't get it all over your shoes," he mutters, wiping his mouth with the back of his hand before he presses his forehead against Regulus' collarbone, making himself smaller than he is. It doesn't take much, and Regulus wants to burn everything to the ground.

"That was one time," he complains in mock-offence. "And I was, what, four?"

Darkly, Sirius blinks up at him. "It was at least five times. And I believe you were six." 

"Well, you are sixteen," Regulus points out as he tries to inconspicuously take Sirius' pulse without getting yelled at, "and going to bed." 

He is, as expected, greeted with a rather exaggerated wail of, "Nooooo." 

"Come on," Regulus groans, carefully guiding Sirius back towards the door. He's leaning into his side heavily now, as if he's four years younger and surrounded by a dark winter instead of a bright room, eyes fluttering, heart racing, skin clammy with cold sweat—and this is bad, isn't it? It's always bad, nowadays. "Your friends all left anyway."

"Not all of them," Sirius grumbles, his breath catching as exhaustion takes its toll; and not everyone indeed, because over the top of Sirius' head, Regulus finds James' gaze—soft and hesitant and young—and stumbles. Like an idiot. 

He almost drops Sirius—which earns him a muttered complaint and a smack to the back of his head—and once he has managed to steady them both, his cheeks are flushed with hot embarrassment and the door seems like it moved several meters further away. Decidedly, he looks anywhere but back towards James. He can't wait to leave, kind of regrets having—

"So, do you like him?" Sirius interrupts Regulus' silent spiral, and honestly, he must be actively trying to get dropped down onto the floor. 

"What?"

"James," Sirius elaborates with a huff, as if Regulus needs elaboration instead of a bypass to protect him from the impending heart attack he suspects to be heading his way right this very second. "He's my best friend. I've never had one before—I want you to like him." 

"He's alright, I guess," Regulus allows. He is not looking back. The door is literally right there, almost in reach. 

"Very convincing."

Defensively, Regulus squares his shoulders. "I exchanged like, two sentences with him so far." 

And there it is, that corner he keeps backing himself into. 

"You could just come by sometimes," Sirius says quietly, in that careful tone he never used to need with Regulus before. "James is always around after class." A sideways glance, somewhere between hesitant and accusing. "He's not as busy as you are, I guess." 

And Regulus isn't entirely sure whether his words are meant to hurt, but they do so either way. 

I'm sorry, he wants to say—because he is around, just not in the way Sirius wants him to be. Because he drops by the infirmary all the time, but he doesn't go in. Sneaks glances through the window on Sirius' door or presses his ear against the keyhole to hear the sound of his husky laughter, reminding him of a childhood he threatens to forget. He couldn't wait to get out of that house, back then. He would have waited, if he had known what it would cost them both. 

"You were here tonight, though," Sirius says after a long moment. He sounds resigned as he turns what could have been the start of a fight back into the kind of olive branch they need all the time now to keep the peace between them. "That was nice." 

"Yeah," Regulus agrees quietly. "It was."

He just wishes it would be enough, too.

They make it barely three steps into the corridor before Sirius goes down. He's leaning into Regulus' one second, crumbles bonelessly onto the floor the next. A moment later, he starts convulsing—and Regulus isn't made for any of this. 

"Sirius?" His voice is high and frantic, his hands are shaking, and Sirius isn't responding. With his eyes rolled back into his head, he twitches and shakes and whimpers, his back arched, his neck strained, his face white as a sheet. Like a ghost, like a—

"Sirius," Regulus repeats, a little louder, a lot more concerned. He's on his knees now, scared out of his mind, sees the still shapes of his parents laid out on the floor of their childhood house, remembers the barely moving form of his brother back in that shed that almost became their last refuge, and he can't do this. It can't be him who's left. 

"Sirius," again—but it's not him this time; it is James. He's running out into the hallway, almost slips when he drops onto the floor beside the brothers, his gaze flicking back and forth between them, concerned but not surprised—and somehow, Regulus can breathe a little easier, because James doesn't look scared. 

"I don't know what happened," he whispers, desperate to prove that whatever this is, it's not his fault. He pulls his arms close to his chest as if they might somehow be guilty, as if there might still be blood on his hands that proves his involvement in everything grotesque and painful, and watches James as he gently turns his brother onto his side, then reaches for Regulus' hand just as carefully.

"It'll be over in a minute," he says, eyes pained, mouth drawn, thumb running back and forth over Regulus' white knuckles. 

He's right. 

Sirius is disorientated when he comes to, then apologetic. James reassures him, Regulus stays quiet.

"How long?" he asks eventually, toneless as the three of them make their way towards Regulus' room, upon Sirius' request. Not the infirmary, please. Just...for one night.

"Few weeks," his brother mumbles now, and Regulus nods, even though none of this is okay. You'd have known if you were there, he tells himself and it sucks, to know that it's the fucking truth. 

"I'm sorry," Sirius says later, when he's hogging Regulus' blanket to his chest, still shivering. He says it painfully slow and full of regret, with his eyes shiny from unshed tears, and as if he's actually got anything to be sorry about. There's dried blood on his lips from where he bit his tongue.

Regulus pats his shoulder, then flicks his nose. "Get some sleep," he says, and then he waits for him to fall asleep and cries his own silent tears. 

When he leaves the room, he almost finds himself right back at where the night began. Two pairs of eyes locked together, a breath caught in his chest.

"He's dying," James states, half-slumped against the nearest wall, and really, Regulus liked it better the first time around. The staring, the handshake, the soft introduction formed out of hesitant words. The beginning. 

This reeks of an end that Regulus has seen coming for far too long. Begged and borrowed time, he thinks. But even that runs out.  

"Isn't he?" James continues, voice soft and even, sad and heavy. It's not accusing, and Regulus isn't sure why he expected it to be, because it's not his fault. But it is. But it's not. But—

"He's been dying for a while," he whispers, eyes fixed onto the ceiling. His vision swims again, and when he lets his eyes flutter closed, his eyelashes clump together with more tears. "I'll do better," he promises, unsure whom exactly he is addressing here. "I'll work harder, I'll solve this, and then I can help him—"

"Regulus," James interrupts. He sounds louder, not by tone but by proximity, and when Regulus blinks his eyes open again, James is right there in front of him, his expression pained and his hand raised as if in question. A moment later, it lands on his shoulder and feels like an answer. 

He waits for the moment to break. For James to say, it's not your fault or he'll be fine or it's not on you to fix this or some other bullshit that will neither be much of a reassurance nor anything close to the truth. He waits for him to mess this up.

But instead,

"What will you do," James asks in a whisper, his hand tightening on Regulus' shoulder, "when you lose him?"

And somehow, that's worse. Because honestly, Regulus has no fucking clue how to answer that.

"And you?" he asks back. His voice breaks, dies right there in his throat, refuses to resurface. He said when, not if. It's always there in the details, the distinctions that matter but fly over his head for far too long. Until it's too late.

James nods—in understanding, not in dismissal—, forces his mouth into something that might vaguely resemble a smile, and bids him goodnight before he leaves. They leave it at that. For years. And for some godforsaken reason, Regulus hates him, too. 

***

"I've found you a partner," Dumbledore declares one day.

Regulus is sixteen, and barely holding on. This, he thinks, is the last fucking straw.

"Howdy, cowboy." Barty greets him with a careless wave from where he's lounging on Regulus' chair, behind Regulus' desk, in Regulus' room—and Regulus frowns in irritation, then decidedly turns around and leaves before he throws a tantrum and loses the very last shred of respect he has around here. 

He works alone. Which is probably why it's such a wonder that he ends up falling in love, of all things—but then again, the world is ending. Stranger things have happened. 

Stranger things will keep happening. 

It takes him six days to actually talk to his new partner, then another six weeks to kiss him.

Barty, for his part, looks equally pleased by both of these occurrences. 

"There you are," he says after the latter one, sounding a little awed, and Regulus is already second-guessing and rerouting and coming undone—but Barty leans back in effortlessly, with teeth and gentleness at once, and somehow Regulus starts to come together, too. 

He didn't know he could do that anymore.

The next months bring a lot of firsts. 

The first time in over a year that Regulus allows himself to cry in front of someone else, and the first time in half a decade that he willingly sinks into the pair of arms that comes up around him as he breaks into pieces, that he accepts the wordless offer of letting himself be held through his agony. 

He is sixteen, and he is so starved for connection that his ribs break around the vacuum of his heart. It's the curse of growing up without many friends, he thinks—but he never needed them, before. He always had his brother.

He doesn't anymore.

Sirius is restless and angry, tired of being sick. And Regulus understands it, he really does—but his organs are working, heart beating, lungs breathing, muscles moving, so maybe he doesn't. His brother likes to point that out, at least. 

Most of their conversations end in fights. Most of their fights climax into angry silences. 

Sometimes, they don't talk to each other for weeks. 

Regulus is tired of it, of the slammed doors and short tempers, of going over the same three arguments a thousand times every single day. He's tired of watching Sirius die, too. Sometimes, he thinks he never really got to see him live. 

Always, he wishes the roles were reversed.

"What's it like," Barty wonders one day, as his index finger trails softly over Regulus' hipbone, "to have a sibling?"

"Horrible," Regulus mumbles, eyes falling shut. When Barty huffs out a laugh, he smiles as if his admission is more of a joke and less than just the truth. 

"So you wouldn't burn down the world for him?"

"I didn't say that."

Haven't you noticed? he thinks. I'm already doing exactly that. 

But sometimes he thinks it's not the world he's burning down. Sometimes he fears it's just himself who he is slowly turning into a pile of charred ashes—but then Barty's fingertips dig into his waist with intent, Regulus reminds himself that even ashes get to burn bright, and it's enough, for another night, or day. He doesn't actually know what time it is. Sleep has never been his friend, in either life.

Still, time passes. It does so differently now, with someone by his side again, someone who refuses to let himself be pushed away, who holds him and hears him and touches him. 

So many firsts. It hurts to remember now, even more so than before. The first one to touch him with gentleness not because he was obligated to do so but because he wanted to—and Regulus loved him, in that way people can love when they hate the world. With tears and blood and teeth and heart. They were never going anywhere but down, but they held each other's hands as they descended, and it meant something, if not everything. 

At sixteen, he didn't know this would end in red blood on white sand. At sixteen, he didn't think it could get worse.

Back then, they were just kids. 

Sirius doesn't like the way Barty and Regulus grow close, but Sirius doesn't like much these days, least of all that he remains chained to his bed. 

"I need to get better," he says, on one of those rare occasions that has the brothers still talking to each other, and Regulus tells him that he will because even now, he cannot bear to even think about the alternative.

When, not if. It's an endless repetition in his thoughts, never quite leaves his mind. He's back to avoiding James; something about him makes his skin crawl—but avoiding James means avoiding Sirius, which means fighting without rhyme or reason or making up. But it doesn't matter.

It doesn't matter that they fight. It doesn't matter that most of the time, Regulus thinks they don't even like each other anymore. It doesn't matter, because Sirius took two lives to save Regulus' once, and Regulus is only one slit throat away from evening out their scores and repaying his duty. His brother won't die. 

Regulus won't let him.

So,

"We need to fucking solve this finally," he tells Barty, throwing a stack of undecipherable calculations right into his face, which is by far the most effective way to wake him up from a nap, Regulus has come to learn. The others are...a little more time-consuming.

"Uh-huh," Barty mutters, still half-asleep. He swats the paper out of his—their—the bed, and turns over to crush his face into the pillow with a mournful yawn and a quiet whimper. "We will. Just after nap-time, alright."

Regulus is ready to argue—he always is, and he always does—but this time, something makes him pause. He blinks as he searches for the source of his hesitation, squints down at the abandoned paper, then swipes his gaze over Barty's half-dressed state, and feels the air catch in his throat. His stomach drops; it's an unpleasant sensation. 

Barty doesn't react when the mattress dips under the weight of Regulus' knees, but he blearily blinks his eyes open when Regulus runs his thumb over the darkening bruise on his cheekbone, his touch lingering as if it might be enough to soothe the ache. 

"Mulciber again?" he whispers. 

Barty sighs as he hesitantly leans into Regulus' palm—and both of them hold their breath. Search each other's eyes. They don't...do that. Regulus initiates a fair amount of contact between them, but soft touches like this aren't usually his to give. It's just—Barty looks like he needs it. Has looked like he needed it for a while now.

"You know it," Barty mumbles, words slurring around a split lip that will take weeks to heal properly, just like the last one did. "He looks worse, though."

Regulus snorts, then smiles. "Want me to poison his food? Because I will." 

In answer, Barty pulls him down into a kiss.

It's only later, that he finally gets it. When he lies on his back next to Barty, two bodies half intertwined, one lax with sleep and the other frozen, locked into his head. Heavy thoughts are holding him down, rendering his body motionless until Regulus feels suspended in air and space and time, until he feels as if he's just about to run out of oxygen and cease to exist. Because he stares at Barty, so easily taking the comfort Regulus still finds so difficult to offer, and he thinks of his brother and of the dozen instances blood was spilled in the name of protection, and he remembers a hand on his shoulder, its gentle pressure tethering him to the present while a singular question unravelled him at the seams—and he's got it. It was right in front of him all this time, just barely out of reach.

"Love," he croaks as, like long-lost puzzle pieces, the full picture finally slots together.

"Hm?" Barty mumbles. His breath is hot against Regulus' neck, but Regulus is already burning with something else.

"Not you," he mutters, even though—yes, exactly him. All of them, everyone, even he himself. "I need to go," he says, but he's already bolting out through the door, leaving and returning at once. "I'll be right back."

But he isn't. Not really.

***

Regulus is used to watching his brother, no matter his age. He grew up studying Sirius, idolising him, analysing him, copying him. There's no one else he's more familiar with, no one else he feels as close to and far away from at once. 

There's no one else he'd end the world for, no one else he'd kill and die and live for.

It's important to remember that. For what comes next.

"Remarkable," is what Dumbledore says to him after Regulus bolts into his office at four-thirty in the morning and changes the trajectory of Crucio's research once more. Intentionally, this time. That matters. 

He wasn't involved in all of it, even if it will always feel that way. His frustrated throw-away comment didn't actually breathe life into the virus that was designed to kill, and the nights he spent wrapped in concentration instead of blankets didn't automatically translate to the downfall of dozens of innocents. 

They ordered him back into that room eventually, but they never mentioned their virus again. They let him work on calculations, on trials that sounded sensible and useful, on tests that he didn't know would turn out to be gruesome and bloody. Before it became dark, it was supposed to be different. 

Three phases. A maze for stress and fear, a wasteland for endurance and strategic thinking, a line of individually tailored simulations to retouch the subject's values at the very end. A bulletproof plan—except that even in theory, it never worked. 

Now, it will.

"It's about the dynamics," Regulus says on that fateful early morning, breathless and lightheaded and grinning in triumph, for more reasons than one. "We've been looking at the potential subjects individually, trying to find the mean for everyone's most effective outcome—but we've been ignoring the most important variable all along; love. Calculate love into the equations and every single outcome automatically multiplies. Stress. Fear. Pain. Anger. You want maximum results? Love is the key for it all." 

Dumbledore blinks slowly, then rubs a hand over his face. 

"We can't manipulate love," he says, but his voice is tentative, already taking on that tone that means he is half-lost to his thoughts, going over his own ideas in high speed. 

"No." Regulus breathes in, then out. "But you can manipulate people in love, just as you can control the circumstances getting them there. A clean slate, a fresh start. Empty heads. Make them care for each other, make them lose each other—and watch your calculations finally become true. It will work, I went over all of it. This is it." 

"A clean slate," Dumbledore repeats, and he's smiling now, getting up, getting to work, getting it done. His hand on Regulus' shoulder. His voice in his ear. "Remarkable."

And wasn't it?

"Will you stop torturing him now?" Regulus asks as he steps in between the man and the door, because he's sixteen and he's tired and he's not stupid. Not anymore.

Because most of the time, he has trouble sleeping, so he wanders the halls at night, trying to outrun his thoughts. Because he knows the code to every door in this building, and when he came across one that refused to open, he made it his mission to find out what exactly they were hiding from him. Because it took him three nights to overturn the circuit and climb into a lower level of Crucio that he was never introduced to. Because he met Remus, and more puzzle pieces fell into place.

"How did you get in here?" Remus had said, minutes before he introduced himself and got a name, back when he was still just a boy. Sirius' age, Regulus guessed, though he wasn't entirely sure. There was something inexplicable in his eyes that made him seem older—but Regulus had studied his own reflection for long enough to have learned just how many lies could be stored in the creases of someone's face, so he wasted no time trying to figure out something that couldn't be solved easily.

"What exactly is here?" Regulus asked instead in return, narrowed eyes daring the other boy to argue—but he didn't. 

He showed him, instead. The liquid nitrogen tanks full of viruses and empty of antidotes. The monitors showing protocols and experimental plans, discarded and resumed a hundred different times. The plexiglass cells with corpses, their unseeing eyes bloodshot, their displayed skin marked by swollen, black veins, their mouths opened in soundless screams. 

"What the fuck," Regulus whispered.

Remus nodded darkly, then said, "There's more."

They needed something scary to carry their new virus, so they came up with that, too. Eight-feet tall monsters, some grotesque mixture of machine and biomass, full of spikes and stings and claws and poison. So many legs, so much slime. Death incarnated. Fear personified.

"Where will they put them?" Regulus asked, unblinking eyes fixed on the start of something horrible. He already knew, but he had to hear Remus say it.

"Inside your maze." He said it as if it was obvious, and it was. A moment later, he glanced down at his watch and sighed. "You should go back up now." 

He seemed resigned—no, he seemed in pain. Absentmindedly rubbing his hip, wincing slightly as he shifted. Regulus narrowed his eyes, glanced at his clothed forearms. 

"Are you alright?" He wasn't paranoid, he was just...careful. 

"Work hazard," Remus shrugged, lifting up his shirt to show off bloodied bandages wrapped around his lower stomach. "Tour didn't get around to the animals yet. They can get nasty."

Regulus blinked. "That's... You should probably get that locked at by someone."

"No shit." Remus rolled his eyes, then let his shirt fall back down. "It's days old already. Antiseptics are free, but stitches only come once they're happy with the progress down here. Pain killers, too." Again, he shrugged. "You know the drill."

"I—"

Did he?

"That's insane," Regulus croaked. His fingers were shaking. Why were they shaking? Oh god. "They're withholding medical treatment until you give them what they want?"

Cautiously, Remus levelled him with a long stare. "It's not just me. We're a team down here; I just got the night watch. Less movement, normally."

"Do they ever," Regulus breathed, swallowed, choked, "hurt you? So that your health depends on your progress?"

"What do you think?"

"I think," Regulus whispered, mind hazy, thoughts a loop of denial and heartbreak, "that I can get you some pain killers. And stitches. And whatever else you need." 

Remus raised his eyebrows in that way that came with being used to things costing far more than they should. "In exchange for what?"

"Nothing," Regulus promised, because Remus already gave him everything. 

Because for more than six years, Regulus watched his brother get better only to get worse again. The constant back and forth, the torturous up and down. Because Sirius stayed chained to the bed, and Regulus stayed by his side, watching him swallow pill after pill as he begged them to work. 

And they had been working all along.

"You need to stop taking those pills," he snapped hours later, crashing into Sirius' room like a man coming undone. And he was. In six years, his brother never left the infirmary—and how could Regulus have been so stupid?

"What?" Sirius snapped back. They hadn't spoken in three weeks. He looked too tired to be angry, too sick to fight—but he tried. Always did. "You mean those pills that are keeping me alive?"

"Are they?"

Sirius faltered. Regulus almost broke down.

Because he took blood out of Sirius' veins and went to find Narcissa. Because he snapped at her not to ask any questions and reminded her that he never asked them either, because he watched how her expression changed from confused to horrified over the course of hours. Because something died in his chest that day. Because he thought he knew what hatred felt like but he really only found it out right then and there, as he stared at the proof of poison in his brother's body. Because he was the one that put it there. 

Because they promised to fix him. 

Because they did not. 

And when Dumbledore cocks his head in faux-confusion and levels him with an impatient smile, still so awfully intent on playing that stupid game of his, Regulus thinks of all the ways he can make them pay. 

"Will you stop torturing him now?" Regulus repeats. His voice is like ice; maybe he never got out of that deadly winter that almost took the brothers' lives. Might have been better that way, honestly. He is shaking with rage, with fear, with exhaustion; and he's yelling too now. "You got what you wanted! I gave you what you wanted. Make it stop, now."

"Regulus," Dumbledore sighs, always belittling him, always acting as if he's nothing but a source of exasperation when he's not constantly delivering the shit Crucio cannot solve by himself. "Let's go over those calculations of yours first, yes? If they are really working, we will talk more about...this."

"No," Regulus chokes, fire thrumming through his veins so hotly it hurts. He's not made to burn like this. "This ends now. He's suffered enough and you got what you wanted, and I won't—"

"There's no definite proof that it will work just yet," Dumbledore interrupts. "Just because your idea sounds promising—"

"You don't get to torment him!" he yells. "What the hell is wrong with you? You—

You gave him seizures!"

In a blink, Dumbledore's expression changes from mildly irritated to cold. "And I gave him antibiotics when he would have otherwise died out there, too. Don't you remember that? He might not be healthy, but he is alive—and you begged me for that, Regulus. I can still hear the despair in your voice and really, you've got to be careful with the deals you make."

"I was a child," Regulus croaks. He was a child, and he was slapped and pushed and punished and betrayed for being one.

"You still are, evidently. Acting like this." He pushes past Regulus as if he was never much of an obstacle in the first place. "Now let's go over those equations."

Regulus follows. His parents towards bloodshed, his brother out into the cold night, Dumbledore down into hell. He has never quite figured out how to go his own way, and he is sixteen and he is a child and he is underestimated and ridiculed and smiled down on and he is done. 

He is angry as, hours later, he stands in the middle of a room full of adults that never took him seriously and never will, as he explains them how to manipulate more children in order for them to get what they want. For the greater good, apparently. 

Too bad he never really cared about that. 

He is a child and he is intelligent and his theory was right and his calculations make sense and he is so fucking angry. Furious really, ready to light up and explode, to not just burn but to blast, to destroy and diminish and wreak havoc on everything. Everyone. 

"You know how to build a bomb? he asks Barty that night. The bruise on his face has started to fade, but it's still there. Regulus wonders if he's ever as angry as he is right now, and when Barty smiles in response, as if he saw the question coming from miles ago, as if he'd been waiting for it, he thinks he might.

"Thought you'd never ask, hotshot."

Over the course of the next year, they build six.

***

He finishes the maze. He started it, in a way, so it makes sense. And there's not much of a choice to be made; never has been, he knows that now, but he does what he can with what he's got. 

Works from Sirius' room now, leaves his side only when someone else will cover his surveillance—which isn't easy. Trust comes even harder for him nowadays. Most of the time, it doesn't come at all.

So he stays on his chair and ignores Sirius' hesitant tries at making conversation. He lost it once, badly, when his brother tried to apologise—but there's no time to talk either way. He calculates, programs, and plans, hunches over his notes until he can recite them backwards, stares at screens until he thinks his eyes might start to bleed.

Every night, someone inspects his work—and Regulus inspects them in turn as they hand Sirius a singular pill. 

It took seven years for him to get better, but he finally does. Regulus' eye twitches. 

"You don't have to do this, you know?" Sirius tries one night, colour in his cheeks, guilt in his eyes, his hand outstretched as if he hopes to breach the distance between them.

"Don't," Regulus snaps. Don't talk to me, don't forgive me, don't make me choose. He is sacrificing those subjects that were once just kids, exactly like the two of them, and it kills him—but he won't sacrifice Sirius instead. He won't. "It's almost done."

Sometimes though, he catches Dumbledore's eye out in the hallways and knows that this is far from over. Neither of them has won, but Dumbledore is not the kind of man to be satisfied with a draw. There's something else coming, he knows. 

Be careful with the deals you make—well, Regulus is. He's learned his lesson.

So, he finishes the maze, yes. He just...makes a few adjustments, too. 

It goes like this:

"Remus," Regulus says, licking his lips as his eyes flick all over the room, not ready to settle. Remus' stomach healed well, and he moves without flinching when he steps closer to Regulus, brows drawn together in question. "I've got a favour to ask."

"I'm listening," Remus says cautiously, and days later, he's following through with it, too. The vial of blood Regulus took from Sirius finds its way into the database, and no one bats an eye. No one even notices. 

"You're sure it'll work?" Regulus checks afterwards, face turned away from the disabled camera in the corner just in case.

"They physically won't be able to hurt him—or touch him. It's the closest to immunity we can get." Lost in thought, Remus chews on the inside of his cheek. "But do you really think—"

"I don't know," Regulus interrupts, tense. Tired. "But whatever happens, I'm not letting these...things touch him. He's suffered enough."

For a moment, Remus is silent. When he speaks again, his voice is soft in a way it hasn't been before. "He's lucky to have you, you know?"

"Not really." Swallowing, Regulus turns to leave. "He'd be far better off without me." 

He's just repaying his debts. A life saved, two throats slit. 

He's getting there.

Slowly, yes, but he uses every single second. Makes them count—because they do. 

He sets Sirius' birthday as the code the subjects will need in order to finish the maze and move on to the second phase. It's a small rebellion, a stupid one that has Dumbledore roll his eyes in ridicule—but it does its job just fine. Distracts the older man enough for him to miss the bombs Regulus builds into the walls, accessible through a loophole in his own coding. 

It will work, he thinks. It has to.

Barty smiles at him as if he hang the moon afterwards, and Regulus uses one of those more time-consuming ways to shut him up. 

It will work.

A week later, he shows up in James' room. He tries not to think of it as weird—and fails. Because it is weird. At least a little, but probably more.

He's got no clue how to wake him up, so he spends a good three minutes just standing there, staring. Which...probably doesn't help the situation. Nor does stepping close to James' side and pressing his palm over his mouth—but at least that works. 

Startled, James jumps up, hands raised in defence, eyes wide in alarm as Regulus pulls back his hand and grimaces.

"Regulus?" James questions weakly. He's squinting now, has one hand pressed against his chest, and shakes his head as if he hopes this is a dream. Or fears it is, maybe. "Time's it?"

"Uh," Regulus blinks. "Like, three in the morning?"

And Regulus expected many reactions to that, but the husky laugh James lets out was decidedly not one of those.

"Well, Sirius mentioned that you don't sleep, so." He smiles, amused—then sobers and sits up a little straighter. "Wait—Is Sirius alright?"

Biting his tongue, Regulus glances away. "He will be, yeah. But, I need your help."

"With...what exactly?"

He looks wary, Regulus thinks. That's probably not the best start. 

"Look." He clears his throat. "I know you hate them."

"Them?"

"Crucio," Regulus mutters impatiently. This is not going well. At all.

As if to sell the point, James' eyebrows shoot up in confusion. He reaches for his glasses. "You're aware that we are a part of Crucio too, aren't you?"

"Ah," Regulus scoffs. "So you're here voluntarily? Doing all of this shit entirely on your own accord and standing behind everything that's going on?"

"No," James snaps pointedly. He runs a hand through his hair, until it looks even worse than before, standing up in pure disaster, all knotted curls and tangled strands. "But I contributed to whatever comes next, and I'm not going to pretend I didn't. At least I'm not acting like something that I'm not."

"Neither am I," Regulus hisses. "I'm not pretending to be better than them."

"I didn't say you were."

"You just—" Slowly, Regulus releases a breath. This is leading nowhere, and they are running out of time. "They hurt Sirius. For years."

Immediately, James' expression softens. "I know. He told me." 

Regulus nods, then swallows. "I have a bad feeling about whatever happens next. This is—I've made it personal now, but I won't let him be collateral damage. Not anymore."

James considers him, then nods slowly. "So, what do you need?"

"If they take him—"

"Take him? Where?"

Irritated, Regulus throws up his hands. "Where do you think?" 

In answer, James blanches. 

"If they take him," Regulus repeats, voice quiet and slow and pointed, "I need you to take them down."

He ignores James' gulp, reaches into his pocket instead. Pulls out the flash drive he and Barty spent the past week preparing, full of documents, calculations, coordinates. A message to himself, if he ever gets it back. To remind himself how to end this—or at least to push someone else into the right direction.

"But what—How on earth am I supposed to do that?"

"You'll figure something out," Regulus decides, because that's not his problem. He's done his part, so he hands James the flash drive, ignores that weird feeling he gets when their fingers brush, and takes several steps away from him, just in case. 

"Great," James deadpans, but his fingers curl protectively around the small device, and Regulus knows he made at least one right decision here. "But why are you giving this to me? If you're so keen on taking down Crucio, why aren't you doing it yourself?"

"Because if something happens to Sirius," Regulus says, forcing his voice to remain firm, "I'm already gone."

For a long moment, they stare at each other. He wonders what James thinks when he looks at him, and if he even remembers putting his hand on Regulus' shoulder all those years ago. If he has any idea that Regulus still hears his words in his head, all the time. When, not if. 

He won't lose him. He'll rather lose everything else. 

"He's your best friend," Regulus says, almost pleadingly. "And you are his. Save him, James. If we can't, no one else will."

"But who will save you?" James whispers, the corners of his mouth downturned, the answer to his question already there in his eyes. 

"I don't need saving." He doesn't deserve it, either. Not after all of this.

Softly, James shakes his head. "I don't believe that." 

Regulus laughs, dry and resigned and so far from that careless sound he was able to produce a lifetime ago. "Maybe in another version of this universe, I made different choices and managed to become someone else. Someone worthy of redemption, or second chances, or—I don't know." He licks his lips, squares his shoulders, feels so fucking young. "But in this reality, I am who I am. And I'm done acting like something that I'm not, too." 

Us and them, he thinks. And a secret third thing, a place just for him. Because he is worse. And he might as well act like it, too.

***

It's all flashes afterwards. And it hurts, even worse than everything before.

He is seventeen, and he has barely lived.

He is seventeen, and they take him, kill him, end him. 

He is seventeen, and he goes without much of a fight because he didn't have much of a choice. 

They come at night, go for the element of surprise. Regulus expected them, just didn't know when or where or why. He can guess the last one, though. It's on him, of course. 

What isn't, these days. 

They press a gun against Sirius' temple, force him out of his bed with unnecessarily cruel hands—and his brother looks scared, but not for himself. They share that, this tendency to care more for the other than for themselves. 

"Sirius," Regulus starts, trying to remain calm even when he's certain he's going to lose it, him, everything. Someone pats him down as if Regulus is the kind of guy to carry weapons with him—and maybe he should be. This whole thing might have gone down quite differently, then. "Just do as they say, alright? It'll be fine."

"Reggie," Sirius snaps, shaking off the hands on him as if there's not a fucking gun pressed to his head, and Regulus hates him, goddamnit. "Stop talking shit, will you?"

He's gotten stronger ever since they stopped putting poison into him, but not strong enough to take down four armed strangers, and judging by the way he works his jaw in frustration, he's aware of that too, at least. 

Don't do anything stupid, Regulus silently begs him. Just this once.

In a bit, it's going to be over. Before though, he takes a moment and makes it his.

He watches his brother, despite the loudly issued commands currently being thrown at them, despite the hands on him and the iron fist of fear around his heart. Regulus watches him, the blue eyes that mark the very beginning of Regulus' consciousness, the inches he grew, the deep lines that formed around his mouth, the lankiness he is starting to lose. The scars he collected over the years, the smiles he gifted him, without ever expecting one in return. If he could go back, he'd do a lot of things differently. They've done so little but they've come so far, and Regulus commits it all to memory, the good, the bad, and the worst, even before he realises what he is doing. 

"The hell I will," he hears Sirius say—which effectively snaps him right out of his trance and straight into alarm. "If you want me over there so bad, you better get ready to fucking carry me or else—" 

"I'm cooperating!" Regulus all but yells, desperate to turn their attention back onto him. Where it's supposed to go, and stay. Where it belongs, for now. It will work. "You can just take me instead, alright? Let him go, and I'm gonna come with you voluntarily. If you look into that drawer over there, you'll find sets of data. I ran several tests already, and my own values always look more promising than his—we can go over it together. It makes sense."

It does, it really does. He made sure of it. And it's impossible to miss the look of betrayal Sirius throws him in response, but Regulus is trying his best anyway. He can deal with that later. Hate sounds so much better than grief. 

"Sweet," one of the intruders acknowledges from right next to him—and Regulus blinks once he realises that it is Ariana, her white coat exchanged for simple black clothing, her dark hair pulled back into a tight braid. "But we're still going to need both of you." She clasps his shoulder, somehow looks so much like her brother and nothing like him at all, and smiles, just a tad too sweet. "Congratulations. On being the first two subjects for our two parallel-run maze trials. I'm sure you will have great things in store for us." 

The world tilts sideways.

"No," Regulus says, though it's more of a gasp, really. A breath punched out of a pair of lungs that dreams about giving up. "No, no, no—you can't do that! You can't!"

He expected them to come for Sirius, hoped, planned for them to agree to take him instead—but he didn't account for this. 

It was supposed to work.

"Wait," Sirius says, losing some of his anger. In front of Regulus' eyes, it gets replaced by apprehension, then fear. "There's two?"

There is. A second maze.

A clean slate, a fresh start—for both of them. Separation, after almost two decades of fighting to stay together. He can't lose him. Not like this. Not—

"Please," Regulus begs, because apparently, he's not above that anymore. He'd sink to his knees if he could, if they would let him, if there were no hands on him, holding him up while everything else crumbles. He'd throw away his last shred of dignity if it convinced them not to throw away his brother's life. "I can't. I can't. He's my big brother."

Ariana falters at his words, just minutely. Her brow creases, her gaze softens, her eyes flick towards the door they only just barged through, and he thinks he's got her, for a moment. But then Dumbledore steps through that very same door, Ariana eases her expression back into something between neutral and stoic, and he knows he's got nothing. He's lost it all. 

"What's with the commotion?" Dumbledore questions, eyes on Regulus. He's not smiling, but Regulus still gets the urge to claw off his goddamn face until there is nothing left but muscle and bone. 

"Well—," Sirius starts, and it's already there in his expression, the proof of him making everything worse for himself.

"No commotion," Regulus interrupts, throwing his brother a cold glare. Shut up, shut up, shut up. Don't you know they'll kill you? 

Sirius narrows his eyes at him, then presses his lips shut—and Albus steps in between them, cutting off their silent communication as he leans close to Regulus and mumbles, "If you try anything stupid—right now or in the long run—he will not make it out of that maze again. I'll make sure of it myself, and I'll guarantee you that no matter how hard you try, you will live on without him. You will see this through, Regulus."

He pulls back, smiles.

Numbly, Regulus stares at him, finds that for once, he's got nothing to say in return, and finally, the fear hits him. Who will he be, without his brother? Without his memories? He doesn't want to find out but he will but he won't survive it and he doesn't want to and—

Unblinkingly, he watches Sirius get pulled out into the corridor. He thinks of poison and mazes and stupid riddles, of those corpses down in the basement, sick with something new. Of those monsters Crucio grew in secret, those lives they destroyed in order to maybe save some others someday, those chances, too slim to really be considered anything but dim. Us and them and Regulus, and maybe that's where he belongs, in one of those mazes he helped to come up with, and then six feet below them. 

There's a sob climbing up his throat; he barely manages to swallow it back down. Chokes, coughs, laughs, convulses. 

He doesn't move but. He is walking, dragged by large hands on his itching skin, and the walls are moving and so is the ground and the ceiling and his stupid big brother when he turns around to find Regulus' gaze, desperate and brave and his but not for much longer and oh god.

"Reggie," he calls. Sirius. There's a haze and a numbness and a rushing sound and someone must be screaming, it's so loud. Too loud. Why is it—

"Reggie. Regulus!"  

He snaps into the past present, briefly, for far too long. Focuses on blue eyes.

How old is he?

"What did I tell you?" Sirius demands. "What do we do?"

He is four and six and ten and seventeen—and scared. Always. Even when he pretends not to be.

"We protect each other," Regulus whispers, screams, thinks. Is he even talking? Breathing?

Sirius nods, desperate, frantic, and scared, too. It's okay to be scared then, Regulus thinks. "Damn right we do. I'll find you, alright? You just focus on staying alive. I'll find you, you hear me? I promise."

It's no use, Regulus wants to say. Whatever they promise to each other, they won't remember. And even if they did—Regulus knows the odds. Calculated them himself. They accounted for losses inside the maze, not because they wanted to but because they needed to. Make them lose each other. Subjects will die. People will die. It might be them. It might be him.

He hopes it's him.

He glances at Dumbledore but can't find him, not at first. Everything looks the same, just walls and locks and doors and an end. 

They shouldn't ever have come here. Should have died out there on the streets instead, lulled to sleep by a deadly winter. Should have died in that house even, back before they knew that the would beyond those terrible walls wasn't much better either. It would have been kinder than this. But the world isn't kind and neither is he, so he turns—and there he is, good—to spit in front of Dumbledore's feet while Sirius uses their very last seconds to yell, "I love you, Reggie."

Regulus doesn't say it back. Not with the fear of never getting another chance to do so, and not with Dumbledore watching. One way or another, he'll say it once this is over—but for now, he thinks it, desperately so. 

On top of a cold table, with hands holding him down and tears escaping his eyes and a thousand memories on his mind as proof, he thinks, I love you, too. Right as he goes under. As they strip the existence of his brother from his brain, as they rip half of his soul out of his body, as they turn his life upside down and sideways and all wrong. As they take him and his reason and leave all but the vague memory of a name while the ghost of his brother's presence quietly whispers its meaning into the deep darkness of his mind but only meets unhearing ears. 

I love you, too, he thinks.

Then, Who?

And when he wakes up with no blue eyes around because he is alone, Regulus is not himself anymore. 

In both the past and the present.

It's like he never fucking left.