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When Nightwing had first been recruited to the Justice League, Clark had been worried about Batman’s reaction. Sure, the man had seemed indifferent during the nomination process, but Batman had been known to be harsh on new recruits. Clark wasn’t sure how he would respond to the fact that on paper Nightwing wasn’t that dissimilar to Batman. Nightwing was also a baseline human (at least as far as Clark knew), who passionately defended his crime-riddled home city. Plus, Blüdhaven was Gotham’s neighbour, and everyone knew that he was fiercely defensive of his home. Who knew how he’d react to having another member of the league operate so close to Gotham.
Yet, despite his initial concerns, no issues arose. Clark eventually felt a little guilty for not having confidence in his friends’ professionalism. Batman and Nightwing worked together well enough, and even when they were forced to work very closely there were no obvious problems.
In fact, within two years Clark had almost completely forgotten his initial concerns over their similarities. When he did recall the comparison, he found it to be rather ridiculous. Over the years he had gotten to know Nightwing, and his personality was quite possibly the polar opposite of Batman’s. Where Batman was a wall of neutrality, only occasionally breaking to ooze disappointment, Nightwing was a flurry of joy, cracking jokes and antagonizing every opponent he faced. While it had taken Clark months to realize that Batman didn’t hate him, the entire League was almost instantly enamoured with Nightwing. His easy smile and camaraderie only augmented by his astounding competence as a hero made him incredibly easy to respect. Sure, Nightwing was Batman-level strict about his civilian identity, but unlike Batman he didn’t use it as a barrier to keep people from getting to know him.
Nightwing was by no means a stranger, which is what made it all the more confusing when Clark found everything he knew about the hero reconstructed before his very eyes.
***
The invasion had been rather run-of-the-mill, at least as far as any alien invasion could be. Unfamiliar beasts roamed the streets, terrorizing anyone who crossed their paths. Clark was, as usual, in the thick of it, fighting off monsters at every angle. At some point, Batman had barked a warning about an unknown biological weapon, and so Clark, not wanting to test the limitations of his Kryptonian biology, was carefully maneuvering his way through the fight.
The battle was long, but eventually the collective work of the League managed to subdue the worst of the monsters, until slowly the battlefield cleared.
Then, just as he thought the last of the monsters had been dealt with, Clark heard a single blood-curdling scream carry across the quiet of the post-battle haze. He turned to find Nightwing on the ground, the remnants of a monster’s claw embedded in his chest, as though it had struck out with a dying lunge.
Nightwing was screaming and openly weeping, his usual ability to endure hell and back with a smile seemingly ripped away from him.
Flying over to him, Clark did his best to evaluate the wound, glancing at it with his x-ray vision. To his surprise, the wound itself was serious, but not so life-threatening to warrant Nightwing’s reaction. No, that seemed to be a result of the bright blue liquid seeping into his chest from the claw.
Nightwing’s eyes were vacant and haunted. Clark reached down to lift him, to take him to get medical attention, but the second he made contact Nightwing flinched back and screamed again, this time using actual words.
“No―Not them, not again! I can’t―can’t do it again! B―Dad―B! Please!” Nightwing wailed.
Clark was frozen, unable to think of how to help.
Batman had no such problem.
In an instant, he was at Nightwing’s side, carefully examining his wounds and calmly moving in to help.
“Nightwing, it’s okay, I’m here. You’re alright,” he said, and oh. Oh. That wasn’t Batman’s voice, the low growl augmented by a modulator. Clark had never heard Batman drop his voice like that.
“B―Dad?” Nightwing responded, so softly and quietly that Clark was sure he only heard it due to his augmented hearing.
“It’s okay chum, I’ll get you out of here,” Batman said soothingly. He pulled Nightwing into his arms and pressed a button on his gauntlet before speaking into his comm. “Evac needed ASAP, Nightwing down with Toxin-like substance. Initiate Fear Protocol.”
Some part of Clark noted that the message did not play through their League comm. He wondered who Batman was calling, and felt guilty for the thought. He hadn’t been able to help Nightwing, but hopefully Batman could. The two heroes were embracing so tightly that Clark felt like he was invading a private moment just by witnessing it.
“Kal,” Batman said, pulling Clark from his thoughts, “I need you to lead the cleanup. I have to figure this out. Can I trust you to deal with this all efficiently?”
Clark knew that Batman wouldn’t leave the League alone after such a battle without dire circumstances, and he couldn't help but wonder what exactly his relationship was to Nightwing that he would drop everything to personally help him.
“Of course you can trust me,” he confirmed before speeding off to get the cleanup organized. As he did, he couldn’t help but replay the words he’d accidentally overheard.
Soft, familiar tones, and a hushed, unsure whisper of Dad.
***
After that moment, Clark didn’t see Batman for nearly two weeks. He didn’t show up at the next League meeting, missing his first ever formally planned League session. Nightwing was also absent.
When Batman did return, he confirmed Nightwing was still healing, but didn’t add anything else. Clark hadn’t expected an explanation, but he couldn’t help his curiosity. Rumours had spread in Batman’s absence. Even the heroes who hadn’t been in hearing distance of his moments with Nightwing had seen the way he calmed the other down, the way he’d personally overseen his medevac. It was obvious that they were bursting to ask questions, and were only halted by having to decide whether asking was worth potentially getting on Batman’s bad side.
In the end no one dared ask that first day, nor the meeting after that. Clark was slightly disappointed, but also glad that his teammates possessed at least some tact (looking at you, Hal). Batman volunteered no new information, and no one pushed for more. Theories spread behind his back, the League’s gossip mill not one to shutter for lack of certifiable information. Clark was not alone in his desperation to figure out the exact parameters of Batman and Nightwing's relationship.
That is, until Nightwing made his grand return to the League two months after he’d disappeared.
In hindsight, Clark really should have expected that the perpetually performative Nightwing would bask in the drama of his return to the League.
It began subtly, with Nightwing arriving at the Watchtower at the same time as Batman, ostensibly both coming from Gotham. They heard his laugh before they saw him, and that alone was enough to get the gathered Leaguers’ attention. As the duo made their way to the meeting hall, Nightwing’s laugh continued to echo through the halls.
“I’m telling you B, next time I’m home we have to watch it,” Nightwing said cheerily. “You might even learn a thing or two.”
Batman was looking at the younger hero and…smiling? Clark wasn’t sure he’d ever seen amusement, let alone a genuine quirk of the mouth on the man.
The room was stunned into silence. All of the burning questions about the two heroes seemed to have evaporated as some of the most powerful beings on Earth found themselves unable to speak in the face of a smile on the Dark Knight’s lips. Clark couldn’t blame them. He had previously thought himself the most familiar with Batman out of anyone in the League, and he was barely keeping it together.
“You’re looking better Nightwing,” Clark eventually offered in an attempt to break the newly formed tension in the room. He hoped the attempt at normalcy would get things back on track.
“Aw thanks Clark. You don’t have to worry though, I’ve been cleared for action for weeks now. I would’ve been back sooner, but someone,” he nudged Batman, “Insisted I remain grounded to regular patrols because he’s secretly a huge softie and was worried about me.”
Batman scowled, but it wasn’t harsh in the way it usually was. No, this was almost teasing, like he was playing along with Nightwing’s dramatics.
“It’s important to heal properly before jumping back into action,” he scolded.
“Yeah, I don’t think you have a leg to stand on there, Mr. “I can still patrol with cracked ribs”,” Nightwing shot back.
“Hn,” Batman replied.
“What the actual fuck is happening,” spoke a voice, undefined yet most likely perfectly representative of every Leaguer’s thoughts, at least if Clark’s were anything to go off of.
“Oh, you guys didn’t know?” Nightwing said with a smirk, “My dad over here is a big baby when it comes to his kids getting hurt.”
“DAD?!?”
“KIDS?!?”