Hello y'all! It's been so long since I've written anything, but I was inspired by this one medical video I was watching (3 am does weird things to you) and with Denki being my fav character in bnha, I thought that it'd be a cool headcanon/idea to expand on. Enjoy!

In hindsight, it should've been obvious that his brain wouldn't be the only part of his body affected. Whenever he exceeded his wattage limit, the shocks fried not only his brain, but his heart as well. The numerous jolts and short-circuiting had damaged the muscle enough that Denki had begun to experience arrhythmia. It wasn't as noticeable as him losing 75% of his brain cells, but the effects on his heart usually lasted longer. It wasn't so much of a problem to Denki, since so what, your heart's beating a little irregularly? Definitely not more detrimental to his well-being than turning into a mindless, drooling lunk-head in the heat of battle, but all those shocks to his heart weren't adding up to anything good either.

Denki found himself avoiding any and all drinks with caffeine in them, even if last minute study sessions at three in the morning begged for just a shot of energy. The first time he found out had been a regular school morning, and just a cup of instant coffee had his heart racing from first period to lunch, leaving him a dizzied mess the entire time.

It wasn't just caffeine either; rigorous exercise was almost always a problem too. For the most part, Denki was fit enough to avoid stressing his heart to extremes, but with Aizawa's hell courses, one would never know. As a hero-in-training, this wasn't ideal—Denki was fully aware—but things would work out, hopefully. Maybe his quirk would shock his heart back to normal, like a defibrillator.

In hindsight, he should have seen this coming. Class 1A had a good ol' battle simulation at USJ, with the class divided in half between villains and heroes.

This time however, the fights were unmonitored and spread out throughout the various environments in the facility. Denki, a villain this time, was thrown into the ruins of a city, rubble scattered throughout and dust clouding the air. And just his luck, he was fighting Bakugou.

The majority of the scuffle was really just Denki running out dodging whatever blasts the asshole aimed his way, moving too much on his feet to be able to discharge a controlled shock. He hopped from side to side, scaled the crumbled remains of buildings—anything to avoid being charred to a crisp by Bakugou's relentless arsenal.

"FUCKING ELECTRIC RAT—STAY STILL!" Bakugou roared from his place on the collapsed apartment roof, a couple feet away from Denki. Three more explosions shook the ground from behind Denki, and with an ungraceful squeak he leapt onto the street and rushed towards cover. A tactical retreat, he told himself. He needed to recollect himself anyways.

During his mad dash towards a still standing four floor parking lot, Denki felt it. Despite the booming madness of Bakugou blasting himself towards Denki, all of it was drowned out the moment his heart skipped a beat. This fluttering was usually a sign of worse to come, and Denki knew he had to dip.

Fuck fuck fuck fuck—Denki's internal chanting propelled him behind a giant pile of concrete on the second floor, where he collapsed against it, gasping out breaths while pressing a hand over his chest. Below him, the sounds of Bakugou's explosions were getting smaller and smaller. Did the violent battle-hungry asswipe not follow him?

As he listened for signs of Bakugou, a wave of dizziness flooded his head, and suddenly he felt pangs in his chest. Denki grit his teeth. How could he forget his current predicament? Feeling his heart gallop wildly and inconsistently against his ribcage, Denki pressed his forehead against his knees, hoping that at least the dizzy spell would go away. His limbs felt like lead, and his breaths were coming out shorter and shorter.

Denki squeezed his eyes shut, waiting for everything to go away like they usually did.

This time however, his body seemed to want to toy with him a little longer. He didn't know how long he sat huddled there, but it wasn't long until he heard footsteps, calm and almost dragging against the concrete.

Panic took over. Did Bakugou come back? Would he still attack? The dude must've had some grams of humanity in him, and at this point Denki was willing to forfeit immediately. Sinking into himself, Denki pressed himself closer to the rubble, feeling the hard edges rub painfully against his back. That's going to leave some bruises. Great.

"Yo Kaminari, you alright?"

Denki blinked. That was Jirou's voice.

He allowed himself to release some of the tension in his shoulders, and taking great care to not make any sharp movements, he poked his head out.

"Y-yeah," he managed, body still curled up and a hand draped loosely over his chest. "How did you find me? And why are you here?"

Jirou eyed him, before lifting up her earlobe-jacks. "I heard you. And I was stuck in this area too. Bakugou almost roasted me alive a couple minutes ago."

"You heard me? Wait no, dumb question. 'Course you heard me," Denki groused. He made to stand up, but wobbled a bit as he shifted his weight to his feet.

Jirou nodded with a "duh" expression, but still moved forward to steady him. She tapped a finger to his chest. "I picked up your heartbeat from the first floor. It was going wild—thought Bakugou left your almost corpse here or something."

Denki only grimaced. "He was close to."

"Mind explaining why you're white as a sheet and look as if you're going to pass out?" Jirou asked, before quickly adding, "Bakugou didn't psychologically torture you did he?"

"To the second part: no," Denki said. A slight pause, and he continued. "And to the first part, I have arrhythmia." It was more of a mumble, but nevertheless, Jirou caught it.

"That's a big word."

"I googled it."

Jirou's eyes were trained on him, and her hand was still on his shoulder. Her silence was a quiet request for him to continue.

"It's another side-effect of my quirk," he stated miserably. "There's a malfunction in the electrical system in my heart from continued shocks. As if turning into a useless, drooling ragdoll wasn't enough."

There was a length of silence, as Denki kept his eyes on anywhere but Jirou, cheeks flushed a shade of embarrassed red.

Jirou remembered the times she had laughed at the after effects of Denki's electrocutions, and suddenly felt a pool of shame in her stomach. Carefully, she extended her hand, and rested it against Denki's chest, right over his heart. It pulsed quickly, but at least it was consistent again.

"You're fine right now, and you will be later," Jirou said firmly. "We'll get you to Recovery Girl, get you some meds, and even install a goddamn pacemaker if we need to."

Denki gripped her wrist. "You think so?" His voice was tentative, a far cry from the obnoxious edge that Jirou was used to.

Jirou moved her hand to flick his forehead, relishing in the satisfying tok sound her fingers created.

"H-hey!" came the surprised cry.

"Of course you dumbass," she scoffed, "these things are fixable with modern technology. What I don't get is why you didn't speak up sooner."

Jirou got a half-hearted shrug in response, and sighed.

"Whatever man. Let's get back to the others—class ended like five minutes ago."

Idk what I was going for in regards to the relationship between Jirou and Denki, but I can safely say that there is at least a bromance. This was written in two parts, where I started this piece like a couple of months ago, so forgive the divide in writing style or something. I also posted this immediately without editing, but et me know what you think, and please feel free to leave critics!

Thanks for reading,

Dingdong