Chapter Text
You picked me up when down I fell
But I'm still standing
Through and through
I know exactly what to do
I'll give it everything I got
Although I'm not stronger than you
But I'll be your shield
I can be your lion
I'll dry your eyes
If I see you cryin'
Believe in me
And I won't let you down
But now we've come so far
I know just who we are
And we shine brighter than
Any gem between us and the sun
Now it's just you and me
Like it was meant to be
And I'll protect you
I'll defend you
If you let me try
~ Let Me Try by NateWantsToBattle
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The blow sent Rengoku stumbling back, his quick movement just barely getting Tanjiro out of harm's way in time. A thin line of blood trickled down over eye where the tip of the spirit’s tail had struck him like a whip, but the defensive crossed shape his arms had made thankfully absorbed the worst of the blow.
“Run!”
The omega's first instinct was to obey Rengoku’s sharp, loud growl, but instead he held his ground as he observed the snake-like spirit. It towered several feet above the alpha, its mouth open in a rage-filled hiss as it glared down at the pests who dared get in its way. It began to slowly circle them, assessing its prey, and from the corner of his eye Tanjiro watched as his professor's hip began to glow.
It was completely different from his aura, this light a deep, burning scarlet like a campfire about to explode into a bonfire. Rengoku reached his hand down, as if drawing a sword, and from thin air a blade made of spiritual energy manifested. It was a katana, the plain-looking weapon thrumming with enough raw power that the omega could feel it from several feet away, and without hesitation the alpha charged.
Rengoku’s strikes were so fast that Tanjiro could barely keep up with them, his professor's attacks a stunning display of disciplined movements and honed technique. The spirit was driven deeper into the forest, its attacks blocked time and again, and Tanjiro was cheering as he watched Rengoku. It seemed like the outcome of the battle would be assured, the snake-like being oozing from several deep cuts as thick, oily globs of black blood scattered across the forest floor.
Then it lunged in, jaws snapping, and grabbed Rengoku.
The alpha was shaken like a stuffed animal in a dog's mouth, his limbs flailing wildly as he tried to pry himself free from its razor-sharp fangs. It flung him down with a disdainful jerk of its head, Rengoku slamming into a tree with an audible, nauseating crunch of bone. His sword began to flicker, the weapon going in and out of existence like it was made of television static, and he groaned in pain as he felt his ribs aching from the impact. This spirit was one of the strongest he had fought, something wrong with it in a way he had never seen, and though it should have been defeated by his third or fourth swing it was still standing strong.
Rengoku slumped against the trunk, breathless and stunned, and though he was running right towards danger Tanjiro couldn't stop his body from moving at that sight. A moment later he was in front of the alpha, the omega skidding to a halt as he flung his arms out defensively. He stood, shaking and wide-eyed, between Rengoku and the spirit, but his feet didn't shift so much as an inch once they were planted.
“Stay back!”
His defiant scream didn't faze the spirit, its eyes unblinking, void-like pools of black ichor. The only thing gleaming in them was hunger as it stared down at the delicious-looking humans, and it began to slither towards the omega with deadly intent. Tanjiro knew logically he should have run, that he wasn't equipped or knowledgeable enough to win a fight that never should have been his, but – just as surely – he knew Rengoku would die if he didn't do something, and that was out of the question.
With a low, pained moan the alpha hauled himself to his feet, Rengoku gripping his sword, but as he swayed unsteadily in place he reached out a hand to brace himself on Tanjiro’s shoulder. The moment they touched a shockwave of energy burst out from them, knocking the snake-like spirit back several feet, and Rengoku's sword began to glow. The scarlet blade started pulsing, strands of bright, jade green – the color of the first plants after a long winter – crackled along the sword like a lightning strike.
The blade began vibrating, a maple leaf pattern racing along its sides as the two colors combined. The edges of the weapon sharpened into focus, the blade no longer flickering in time with Rengoku’s labored breathing, and the belly of it extended to make it a thicker sword.
“By the stars…I've never seen…”
Rengoku’s reverent, strained whisper caused Tanjiro’s head to whip to the side to see what had his professor's attention, the omega's eyes going wide when he spotted the transformed blade. He could feel their intertwined energies, the ebb and flow of them as Rengoku’s slid down the sword alongside Tanjiro’s, and for a moment he panicked.
Had he broken it!?
It didn't look broken, but if his energy had tainted it, or had rendered it useless, then it would be his fault if they di…
Before Tanjiro’s thought could spiral further Rengoku was moving, his breathing already at a certain rate and shallowness to most efficiently regulate the ache in his two cracked ribs, and he was moving past his student in a blur. He could feel how much stronger and studier his sword had become despite his own energy lapsing from pain, and there was no time to waste. The alpha dashed towards the spirit, who was regaining its senses from the recoil of the energy burst, and as soon as he was in range Rengoku screamed in primal defiance as he swung with all his might.
The blow cut the spirit in half, the two pieces separating from each other with a sickening squelching, and its body began shaking as a jagged line of green flame started to eat away shadow along the two halves of its stomach where the sword had cleaved it. Its form began to writhe and flail as it roared, Rengoku barely dodging in time as he rolled to the side in order to avoid its thrashing torso, and he was splattered with acidic, dark blood that made tiny, steaming holes in his jacket.
He dashed back to Tanjiro, grabbing the omega and pulling them behind a thick tree to shield them from the rain of blood, and Rengoku didn't let his student out from where he had covered them both with his jacket until the sounds of the snake-like spirit's death throes grew silent. When the forest was once more calm the alpha poked his head out from under their makeshift shelter, eyes darting around as he wearily took in their surroundings. His sword had dissipated, one arm instinctively wrapped around Tanjiro while the other held his jacket in place, and he inhaled deeply as he gratefully drank in the sweet smell of maple.
They had released their pheromones during combat, their heightened emotions shattering the control both men usually had, and Rengoku could have happily stayed wrapped in that soothing scent forever. It felt like home, even the sting of his injury feeling less severe as his respiratory system delighted in the way the molecules settled along his skin. He was never going to be able to eat a plate of pancakes with maple syrup on them or walk under maple trees the same way again.
Tanjiro leaned out, mimicking his professor as he, too, scanned the woods. He was the first to notice the subtle, green glow, the omega rising to his feet on autopilot.
“Tanjiro, be careful…”
Every move was instinct, Rengoku sensing Tanjiro's need to go to the light, and the alpha followed close behind rather than trying to stop him. Where the spirit's carcass lay, the shadowy corpse already melting into the earth with a low hiss, the green flame that had been infused with Tanjiro’s energy was revealing the blue, shining form of a small, excitedly-twirling hibakari keelback snake. When it saw Tanjiro it slithered in the air to him, no malice radiating from it now, and the little snake spirit playfully circled the omega. It began talking to Tanjiro, and though Rengoku couldn't hear it – just like with Yuki – he was able to understand enough of the conversation through Tanjiro’s replies.
Thank you for freeing me from my anger.
“Why were you so angry?”
The omega held his hands out, letting the spirit rest there, and though he didn't know if it could feel him he reached out and gently stroked its head.
The other day humans dammed the river I guard. Some humans said no, others said yes, there was a fight and blood was spilled in my water. The ones who said yes won, and now they leave corpses in my home.
Tanjiro turned to Rengoku, his brows furrowed.
“Was a dam put up around here recently? Maybe one people were arguing over? He's a river spirit, and says something bad happened to the river he guards.”
The alpha shook his head, but nearly as quickly realization struck.
“There wasn't one put up yet, but there's been arguments over a company who wanted to dam the Hebi-gawa river just south of the university to make a larger commercial fish farm to expand their profit intake. The locals have denied their petition several times, and the bill won't carry through, so there's no worry about that.”
Too late.
Tanjiro frowned, the omega updating Rengoku’s knowledge.
“I think they illegally dammed it anyway, and if the police look there might be a couple of bodies in it from an altercation between the two groups.”
Rengoku’s blood ran cold: three days before two of the village men had disappeared, and there had been workers from the company there at the time, so maybe…
“Can you ask if it was two bodies?”
Yes.
The omega nodded, Tanjiro’s stomach twisting at the look of worry on his professor's face.
“Yes. Oh, and just so you know he can understand you.”
The alpha nodded, keeping that fact documented on his rapidly-growing mental list of ‘weird, even for me, things that happen when I'm around Tanjiro Kamado’. Of course the spirit could understand him, why wouldn't it be able to? He bowed to it, even though the move made his ribs scream in protest, and he held the posture to convey his gratitude for the information. He'd be able to bring it right to his friend Giyu Tomioka, the village's head police officer who was aware of the Rengoku family duty, and he would be able to launch a proper investigation that didn't have ‘a scary snake spirit told us this’ written into the official reports.
“Thank you, river spirit. We will leave you now, and you have it on my honor as an exorcist that your river will shortly be returned to its correct state. Please forgive our kind, and I pray you will be at peace once you return to your duty.”
It happily twirled itself into a spiral, showing its acknowledgement of the alpha's words, and with one last cute, thankful little boop of its snout to Tanjiro’s cheek it took off. They watched until its sapphire light faded into the trees, and once he was completely certain the spirit was gone Rengoku collapsed to knees.
“Kyojuro!”
Tanjiro’s startled cry rang out, the omega dropping down alongside him, and he instantly put his arms out to catch his professor. Rengoku was laughing, though, a huge smile on his face as he leaned against Tanjiro’s shoulder.
“You're amazing.”
Had the alpha hit his head? Was he hallucinating?
“What?”
He looked up at the omega, Rengoku pushing himself down further so he could lay on his back for a few minutes. He inadvertently pulled Tanjiro along with him, the duo staring up at patches of brilliant, starry sky where they managed to shine between the wind-swept tree tops.
“I said, Tanjiro Kamado, that you're amazing. If your energy hadn't been there to support my blade then the spirit would have been eliminated, instead of freed, and it could have been months before anyone made their way up river into the mountains enough to check on the dam area. You saved a substantial amount of time and effort for our thin-spread police force, and the families of the men will have closure sooner thanks to you.”
When they had gone downwards Tanjiro’s head had ended up on his professor's shoulder, the two of them laying there in companionable comfort. The omega didn't know how to respond to such a wonderful compliment, and all he could do was shake his head.
“I didn't do anything, so there's no need to thank me! You were the one who fought and got hurt, and you saved my life. If I had been out here alone when it attacked I'd be dead right now.”
Rengoku very much doubted that.
He shook his head, the omega able to feel the movement, and Tanjiro couldn't stop the grateful smile that lifted his lips. It felt incredible to have someone who believed in him, even if it was misplaced, and without thinking he reached for Rengoku’s hand. His fingers curled around it, instinctively seeking the alpha's warmth, but almost as soon as he had done it he tried to pull his hand back when he realized what he was doing.
“I'm so sorry! I didn't mean to make you uncomfortable, and I was happy so I took your hand without thinking…”
The alpha's fingers laced into his, the world seeming to hold its breath as their hands connected. Tanjiro flushed, half embarrassment and half something he didn't have a name for, and his heart sped up far faster than it had any reason to.
Why did this feel so right?
The same thought was echoing in two minds, Rengoku’s thumb gently rubbing along the side of Tanjiro’s finger where it rested.
“It's okay, I don't mind. Nothing about you makes me uncomfortable, and I promise I'll tell you if something ever does.”
Tanjiro gave Rengoku’s fingers a tiny little squeeze, his smile returning thanks to the alpha's reassurance.
“I'll do the same, and for the record I think you're incredible. I've never seen anyone fight like that, and you were so brave!”
It was Rengoku’s turn to question things, his eyes closing as he tried to understand Tanjiro’s perspective.
“Brave? I have to disagree with you there, Mr. Kamado. I wasn't brave, I was trained to do this from a young age, but you? You stood in front of me, weaponless and shaking, yet you didn't back down for a second. That is bravery, in its purest form, and I can never thank you enough for putting your life on the line for me.”
It was the omega’s turn to shake his head, Tanjiro already rebuking the alpha's jaded view.
“I wish you could see yourself as I do, because, duty or not, putting yourself out there to save others – and you can't tell me you've never done that before in different ways – is one of the bravest things I can think of! I don't care if you've had to do this since you were a child: you still wake up everyday now and make the choice to continue fighting something most people could never know about, much less understand, to keep others safe, and to me that's brave.”
A hot, uninvited tear trickled down Rengoku’s cheek, the alpha wiping it away with the hand not holding Tanjiro's. So few people had acknowledged his work that he didn't know how to respond to hearing such high praise, and he let a quiet chuckle slip as he rested his cheek on the omega's head.
“Let's compromise: I'm brave, and you're amazing, and as long as we feel that way about each other we aren't allowed to protest it again. Deal?”
If only he could have seen the brilliant, sweet smile that lit up Tanjiro’s face.
“Deal. Now, let's get out of here and get you to the hospital.”
Rengoku didn't want to move, the alpha happy to stay that way forever as long as he didn't shift his ribs, but his student was right. He did need medical attention, but he wouldn't be going to the hospital. He had another friend in the village who knew about his special line of work, a nurse named Shinobu, and she would make a house call any time he got hurt in the line of duty so that he could avoid having a mile-long list of injuries and hospital visits under his name.
“Actually, if you can help me get home I have a friend who helps me after incidents like this. She makes house calls for my family, and is used to seeing me in less-than-perfect shape.”
Tanjiro jolted up, the omega climbing to his knees, and just as quickly he bent down to lend Rengoku a hand.
“Alrigh, then – let's get you home.”