HINT #1- The time Kaminari's instincts kicked in during combat training.

Kaminari's first slip up happened during a combat exercise, this time with no quirks allowed. They had begun to become more and more frequent with every villain attack, and Kaminari was starting to find it harder and harder to keep pretending. His classmate's moves were always just so predictable and easy that it was hard for him to believe that they had improved at all. The fact that Aizawa always encouraged them and praised them for "being better than he was at their age" never ceased to grate Kaminari's nerves. If Mr. Aizawa was telling the truth, then the heroes really needed to step up their game. If he was lying for their benefit, Kaminari didn't think that was any better. The way he had gotten to be as good as he was was because of the harsh criticism and punishments he received from his parents if he met anything less than their standards for the day.

Of course, he never wanted his classmates to endure what he went through, but Mr. Aizawa needed to be at least somewhat less lenient with them if he wanted them to improve.

"Kaminari! Bakugou!" Aizawa's voice snapped Kaminari out of his thoughts. He instinctively relaxed his shoulders, flashing Bakugou a wide smile. "You're up!"

Kirishima whistled lowly and put a sympathetic hand on Kaminari's shoulder. "I wish you the best of luck, bro. Try not to die."

Kaminari snorted. "I dunno, man. I'll try, but I think I could kick Bakugou's ass if I wanted to." He was right, of course, but no one else had any way of knowing that.

"WHAT'D YOU SAY PIKACHU?" Kaminari smirked. There he was. "I'LL BLOW YOUR STUPID DROOLY FACE OFF!"

"No quirks allowed, Bakubro!" Kaminari chirped, casually flashing Kirishima a thumbs up over his shoulder as he began walking toward the sparring ring.

"I DON'T GIVE A SHIT! I CAN STILL KICK YOUR ASS!" Bakugou followed closely behind him, stomping all the way. "DON'T THINK FOR A SECOND THAT I'LL GO EASY ON YOU!"

Kaminari merely waved him off. He found it hard to believe he was ever wary of Bakugou. He was basically the equivalent of a baby throwing a vulgar temper tantrum. He climbed the steps to the sparring stage, winked mockingly at his observing classmates, and made his way over to the left side of the ring. Bakugou snarled at him and stalked toward the right side, anger coming off him in waves.

Kaminari relaxed his muscles and leaned back, resting his elbows on the bar being him, and contemplated his strategy. No quirk combat exercises were simple: if you knock out your opponent, you win. If you immobilize your opponent, you win. If it takes your opponent more than five seconds to get up, you win. No quirks allowed.

Quirk combat exercises were held on the same stage the students had fought on during the sports festival. Hand to hand combat exercises like the ones they were doing right now were held in what looked like a simple boxing ring behind the dorms.

Kaminari cracked his neck. Out of everyone, Bakugou's moves were the easiest to read. His fighting stance and the way his muscles were pointed practically screamed out his next dodge or action, and sometimes it was so blatantly obvious that Kaminari had to wonder why his explosive friend was considered one of the best in their class at close combat.

Kaminari would just do what he always did. He would follow his opponents move, dodge his attacks, let himself get grazed a few times, throw a few useless punches, and after about a minute, purposely get hit in the face and pretend to be knocked out.

Simple enough.

Until it wasn't.

"Start!" Aizawa's voice was faint from across the courtyard but still audible. Kaminari got into a fighting stance (though he purposely made it sloppy) and eyed his friend lazily. In turn, Bakugou growled and went running in his direction. Kaminari rolled his eyes. Typical. I knew he'd do that.

As soon as Bakugou was in punching distance, Kaminari expertly dodged to the right, Bakugou's fist connecting with nothing but air. The explosive teen growled dangerously, whirling around to meet Kaminari's golden gaze.

"Just give up now." He snarled, a murderous glare plastered on his face. "You're useless against me in combat."

Useless.

Kaminari went rigid. He hadn't heard that word in a long, long time.

As if a switch had been flipped, Kaminari's eyes went widened and instinct took over. No longer was Kaminari fighting to lose. Now, he was fighting to survive. All it took was that one word, one word, and all of Kaminari's memories that he had worked so hard to suppress over the past two years came flooding back. Useless. It was a word Kaminari associated with pain, torture, and death.

Bakugou had a gun to his head, and he'd squeezed the trigger without even knowing it.

xxx

Kaminari's mind went blank. He didn't have to think as he did this. He never did. It was second nature.

Kaminari's hand met Bakugou's incoming fist, twisting it until a sickening crack could be heard, eliciting a howl from the explosive teen. The friend in Kaminari would've stopped immediately at Bakugou's cry of pain, but the assassin in him didn't even register it. It was just background noise, a distraction from the job he was supposed to be executing, the job he had to complete it he didn't want to be relentlessly cut, tortured, and starved for weeks to come.

Unfortunately for Bakugou, the assassin was in complete control right now.

Kaminari wasted no time. He twisted Bakugou's arm behind his back and curled his leg around his opponent's calf, sweeping it out from under him and sending them both crashing to the ground before Kaminari expertly flipped himself so he was kneeling on top of Bakugou's sprawled form.

He brutally shoved Bakugou's arm upwards, roughly dislocating his elbow and making it go limp. Before he could even cry out, Kaminari dug his knee into Bakugou's back, pinning him down and stealing the air from his lungs, before delivering a swift chop to the back of the neck, expertly hitting a nerve just right to immobilize his opponent fully.

In all, Kaminari's takedown had lasted less than three seconds.

Out of pure instinct, Kaminari rose his hand to deliver the final blow, just like he'd done a million times before to a million different victims. He'd been here before. The sight of his target lying unmoving on the floor and being unable to do anything other than await their execution was nothing new to him.

So why was he hesitating?

Bakugou.

The name sent a shiver down Kaminari's spine. It was familiar. It was comforting. It was safe. It was...

It was the name of the person he was currently suffocating.

Kaminari stumbled back with a gasp, causing Bakugou to cough violently at the sudden intake of air.

The blond scrambled away from his fallen friend, panic evident in his eyes and mouth searching for something, anything to say. What had he just done?! He'd almost killed Bakugou! One of his best friends in the entire world! The very same person he had been prepared to give his freedom for just a few short weeks ago!

Kaminari clambered to the far side of the ring, clumsily tripping over his own feet as he tried to put as much distance as possible between him and Bakugou's still form. He'd been doing so good at controlling his impulses, so good at ignoring the instinct to kill again. And in the end, he'd almost lost it, all because of one stupid word. Kaminari curled in on himself, keeping his eyes trained on Bakugou as he watched his back rise and fall intently.

Reassuring himself that his friend was still alive.

Trying to pretend that he hadn't almost sliced Bakugou's neck.

"KAMINARI!" Kirishima's jubilant voice snapped the blond out of his thoughts. He turned to his classmates with wide, frightened eyes, mentally bracing himself for the onslaught of insults that would inevitably be thrown at him. They would hate him. They would think that he was a monster. They would shun him, kick him out, make him go back to the home he had so desperately tried to escape from, make him-

"THAT WAS FUCKING AMAZING BRO!"

Kaminari snapped to attention, gears turning in his head before finally clicking into place. This was a combat exercise. His classmates had been standing far away. From their vantage point, all they could see was Kaminari kicking Bakugou's ass. Kaminari was torn between laughing at the sheer idiocy of the situation and crying over their naivety.

To any trained assassin, Kaminari's intent to kill his opponent would've been blatantly obvious from the moment his instincts kicked in, even from that distance.

However, his classmates were just kids, and his teacher was nowhere near as experienced or observant as a trained professional.

The bottom line was, they hadn't seen how close Kaminari had been to murdering Bakugou. Kaminari doubted Bakugou himself had even realized his intentions. The nerve Kaminari had pinched shut down all pain receptors, as well as paralyzing the recipient.

As far as Bakugou knew, he'd just gotten the air knocked out of him, nothing more.

Kaminari wanted to scream. It didn't matter if anyone knew how freaked he was, just what kind of monster resorted to almost killing one of their best friends because they said a single word?! What made it worse was the fact that Kaminari knew Bakugou hadn't even meant anything by it! It was just his regular, violent taunts that Kaminari heard every single day.

"KAMI, HOW THE HELL'D YOU DO THAT!" Sero's voice brought him back. Kaminari instinctively relaxed his shoulders and straightened his face, expertly plastering on a bright smile at his approaching classmates. It was scary how easily he could put on a foolproof mask. "YOU KICKED BAKUGOU'S ASS!"

"Yeah!" It was Midoriya's turn to shout now, the greenette looking at the electric blond like he held the stars in his hands. Kaminari fought back a bitter laugh. Boy, if only he knew. "I don't know what happened, but you took him down in three seconds flat! It was like you weren't even trying! Where'd you learn how to do that! Kacchan didn't stand a chance!" Midoriya's brow furrowed. "I didn't know you could fight like that, though. No offense, but you rarely win matches, and you've never demonstrated combat skills like that before, and-"

"Problem child." Aizawa's chilly voice cut through Midoriya's rambling like a knife, silencing the younger boy.

Wordlessly, Aizawa knelt by Bakugou's still form as all the other students surrounded Kaminari. He carefully flipped Bakugou over onto his back, eliciting a small gasp of pain and a groan from the boy. Kaminari winced. Though it was no problem for him now, Kaminari had gotten his joints popped out of their sockets enough times to know that it hurt.

"Sprained wrist and dislocated elbow," Aizawa concluded finally, carefully sitting up Bakugou's limp form the best he could. "I'll page someone to get him to Recovery Girl." Kaminari breathed a sigh of relief, which was stupid because of course he knew the extent of Bakugou's (relatively minor all things considered) injuries. He stilled when Aizawa fixed him with a steely glare. "Kaminari wins."

Cheers erupted from Class 1-A. No one was particularly worried about their resident explosive boy (since they all knew he'd experienced much worse, and he'd personally blow their heads off if they showed him any sympathy). Instead, they all focused their attention on clapping Kaminari on the back and shooting rapid-fire questions at him from all sides.

"Kaminari, what the hell was that?!" Mina.

"That was the manliest thing I've ever seen you do!" Kirishima.

"Why have you never demonstrated these skills before, Kaminari?" Todoroki.

"The hell?! What the fuck was that all about?!" Jirou.

"Ah, it seems you've been keeping up with your training, my friend!" Iida.

"Bro, you just took down Bakugou! Not even Todoroki or Midoriya has even gotten close to that!" Sero.

"Kaminari, I must say I'm very impressed." Tsuyu.

"Ahem."

All eyes turned to Aizawa, who was currently handing Bakugou off to Present Mic. The teacher took Bakugou in his arms carefully, flashed a wink at Aizawa, and bounded away with Bakugou gathered to his chest. Everyone fell silent as Aizawa turned to stare at Kaminari, who gulped in anticipation.

"Kaminari. Be honest with me. Where did you learn to do that?"

Kaminari flashed an easy smile, expertly ignoring the piercing, expectant gazes from his friends. "Seriously, Mr. Aizawa. I have no frigging idea." Lies ran off his tongue like honey. "I just saw an opening and went for it. It was all luck, no joke! I don't even know how I took down Bakubro. My mind was just like BAM! And the next thing I knew, he's on the floor! It's a miracle, honestly."

The rest of his classmates seemed to accept Kaminari's answer, much to the blond's relief. After all, who would have believed that Class 1-A's resident idiot took down someone as strong and fierce as Bakugou?

Aizawa, to his credit, wasn't nearly as convinced.

"That's a lie."

Kaminari turned sharply to face his teacher, his easygoing smile dropping from his face in an instant. It appeared Mr. Aizawa was more skilled in the art of deception than he'd thought. Most people would accept Kaminari's answer wholeheartedly, his honest tone, playful words, and seemingly genuine smile faking truthfulness like a pro.

There were only two ways Aizawa could've noticed that Kaminari was lying. Either the blond had messed up somewhere in his explanation, or his teacher had been watching closer than the electricity user had thought.

Regardless, Kaminari was an expert in these situations. If someone questioned something, the best thing to do was deny deny deny until you had a reason not to anymore.

"What? No, I'm not." Kaminari scoffed, rolling his eyes dramatically. "Do you honestly think I'd be able to take down someone as strong as Bakugou without literally every ounce of luck the universe has to offer at my side?" He added a playful hilt to his tone in an attempt to sell the act even further.

Aizawa still wasn't buying it.

Seeing this, Kirishima raised a tentative hand and offered a small smile. "All due respect sir, but I'm fairly certain that Kaminari's telling the truth on this one." His statement was met with murmurs of agreement and nods from the rest of the class. Kaminari made a mental note to be extra nice to all of them in the coming days.

Aizawa narrowed his eyes. "That's where you're wrong, Kirishima." Everyone fell silent. Kaminari raised an eyebrow, expertly feigning confusion though his mind was practically screaming at him. "Kaminari's moves looked precise and executed perfectly. His hits were calculated. In fact, I have yet to meet a single pro hero that has that level of hand to hand combat skills." Hushed whispers circled the class, but Kaminari paid them no mind. He was focused on Aizawa and Aizawa alone. The teacher crossed his arms. "Plus, Kaminari hit a nerve on Bakugou's neck just right in order to paralyze him. There's no way any of that was just 'luck.'"

Kaminari's eyes widened a slight margin before he let out a giggle. "Well, I guess I can't hide anything from you, can I Mr. Aizawa?" Eighteen bewildered classmates fixed their stares on the electric blond, but Kaminari just waved them off with his trademark smirk. "You got me. I've been watching a shit tone of dance tutorials on YouTube these last few weeks or so. To help me become more coordinated, you know? Anyway, one of the moves is this really complicated spinny thing, and I've been trying to perfect it for weeks." He made sure to strain the last word a little bit. "All I did was incorporate into my fight and bam! Bakugou was on the ground."

"Ah!" Iida readjusted his glasses with one finger. "Is that why I've been hearing all of that bumping around for the past few nights?"

"YES!" Kaminari tried to keep the relief out of his voice. That "bumping around" was actually him sneaking out of through the balcony at night to go practice at the training grounds, but Iida didn't need to know that. Besides, having one of the most reliable students in the class reinforcing his story was almost a surefire way to convince Mr. Aizawa that he was telling the truth. Kaminari made a mental note never to call Iida a goody-two-shoes ever again. "Exactly. That was me honing my amazing dance moves."

"Makes sense." Mina murmured. "I've seen Kami dance before. He's pretty boss."

Aizawa crossed his arms, ignoring Mina completely. "And the nerve?"

"Ah." Kaminari smiled easily. Everything was falling into place. "When I first got my quirk, I would sometimes wake up paralyzed in the middle of the night. We went to the doctor to see what was causing it, and he said that my electricity had been turning that nerve on and off for the past few weeks at random. He showed me exactly where it was and how to hit it just right, so if I accidentally paralyzed myself again, I could just push it and continue like normal." It was all lies, and Kaminari knew it, he hated himself for it, but the suspicion in Aizawa's eyes had lessened a great deal. Kaminari knew it was only a matter of time before he believed him completely. "When I accidentally flipped Bakugou over with my incredible dance moves, I saw the nerve and reacted without thinking."

Aizawa nodded slowly. "And his injuries...?"

Kaminari grimaced. That was a question he didn't have to lie about. "I wasn't thinking! I never meant to hurt Bakubro intentionally. I would never! I'm really, really sorry, and I feel super bad." He locked eyes with his teacher. "Seriously. I never wanted to hurt him as badly as I did. He's way too important to me."

That seemed to do it for Aizawa, who fixed Kaminari with a steely glare before turning to the rest of his students. "We're wrapping up for today! Those of you who didn't get to participate in your matches will go tomorrow. Clear?"

"YES, SIR!" The class chorused. Aizawa nodded in approval before shooing them out of the ring with a flick of his wrist, telling them to head to the locker rooms and change back into their regular uniforms instead of their training clothes.

Kirishima jogged up to Kaminari, fixing him with a cheesy grin. "I gotta say, bro. Mr. Aizawa had me worried there for a hot minute."

Kaminari smirked good-naturedly. "Whatcha mean?"

"I mean, for a second there, he had me convinced that you were some sort of high-level combat military assassin dude." He slung an arm around the blond's shoulder. "No joke, Kami."

Kaminari snorted. "As if, bro."

Honestly, Kirishima had no idea how close to the truth he really was.