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A Promise Between Friends

Summary:

Katsuki and Izuku were friends, once. When did Katsuki first start hurting Izuku? He doesn’t know. He doesn’t even remember afterward.

Notes:

(See the end of the work for notes.)

Work Text:

At age five years old, Katsuki Bakugo and Izuku Midoriya were best friends. Katsuki had an excess of kids who wanted to hang out with him. He came up with the most creative games. The teachers said he had the most heroic quirk, which was the instant road to popularity in kindergarten. But Katsuki felt like Izuku was the only one who could keep up with him. Izuku talked so fast it could be hard to follow, but he had the most fun ideas. When Izuku played the villain in games, he was so scary that it felt real. In the sidekick role, Izuku always had the most interesting suggestions for using Katsuki’s new quirk.

Unfortunately, Izuku was not popular. Ever since he’d been diagnosed as quirkless, the teachers looked at him with either scorn or pity. It trickled down to the children. They didn’t know why, exactly, but the adults treated Izuku like lesser so it must be true.

And it had gradually been getting worse. Before, Katsuki’s popularity had been enough to get Izuku into the games at recess. The last couple times, the murmurs had gotten loader. Something was building up to a breaking point.

Today, Katsuki stood over the chalk hopscotch squares drawn on the pavement and proclaimed, “The ground is lava! Anyone who falls, dies.”

A chorus of “Ooooo,” went up from the half a dozen boys around him.

“Kacchan!” Izuku approached with a big grin, waving. “What are we playing today?”

Loudly, Tsubasa asked, “What’s Deku doing here?”

Izuku said, “I’m here to play hopscotch.”

Katsuki winced. Sometimes Izuku just couldn’t read the mood.

Suzuki, a boy with glasses and a laser eye quirk, sniffed. “This game is too hard for a quirkless loser. You’d fall into the lava and die.” A laugh went up from among the other boys.

Tsubasa nudged Katsuki. “Come on, tell him that he can’t play with us.”

All eyes were on Katsuki, including Izuku’s big, green ones. He sweated so badly he feared he’d set his clothing alight. If Katsuki tried to include Izuku, then what if he got kicked out, too?

Katsuki cleared his throat. “Nah. This game is too dangerous.” His voice sounded hoarse, lacking his usual confidence.

“But—” Tears ran down Izuku’s cheeks, choking off his words.

Katsuki growled, “Go play on the swings, Deku.”

Everyone laughed as if this had been a clever insult.

As Izuku slunk off, Katsuki winked frantically at him.


After recess, Katsuki found Izuku in the hallway. “I didn’t mean what I said. It was just a joke.”

“A joke?” Izuku asked, sounding painfully hopeful. His eyes were puffy and red.

“Exactly! That’s why I winked at you.” Katsuki winked again. “From now on, if I wink when I say something, I don’t mean it. You understand, right? We’re friends, so of course you’ll understand my secret signals.”

“I understand,” Izuku whispered.

A leaden pit formed in Katsuki’s stomach. He tried to make his tone jolly. “We’re still going to be hero partners someday. You and me. Just like we always planned.”

Looking at his shoes, Izuku said, “But I don’t have a quirk.”

Katsuki grabbed his shoulders. “It doesn’t matter. I’ll be strong enough for both of us. You can keep giving me cool ideas about how to use my quirk, like you always do. We’ll be a team. I’ll force them to let you become a hero, because I’m going to be so awesome that they’ll beg me to attend U.A.”

Izuku finally smiled. “Really?”

“Really. I promise,” Katsuki said, but then Suzuki passed and he had to leave before anyone saw him talking to Izuku.


Katsuki liked visiting Izuku’s house. Aunt Inko was the best cook, and Izuku had loads of hero merchandise. Best of all, they could play without anyone else interrupting. Izuku was starting to understand that he couldn’t approach Katsuki at school. As compensation, Katsuki tried to visit Izuku at his house more frequently.

They’d spent the afternoon watching All Might videos. Izuku was great at pointing out details about All Might’s quirk. Katsuki had never realized before that All Might seemed to have something like a danger detecting sense.

Mr. Midoriya wasn’t usually home, but today he’d joined them for dinner. Mr. Midoriya was very tall and had scary crimson eyes. Not that Katsuki was scared of some businessman! He was a future hero. He feared nothing.

After dinner, as Aunt Inko cleared the dishes, Mr. Midoriya volunteered to walk Katsuki home.

The air was cool, an autumn breeze blowing through the colorful trees. Mr. Midoriya didn’t talk for most of the way. Katsuki kicked the leaves and dreamed of becoming the next symbol of hero society.

Rather abruptly, Mr. Midoriya said, “You’re the only child who still comes over to play with Izuku.”

Katsuki’s shoulders tensed. He knew that Izuku didn’t like to talk about what happened during school hours at home. Aunt Inko had remained in the dark. It surprised Katsuki that Mr. Midoriya had noticed, especially when he was away on business trips so frequently. Softly, Katsuki said, “I’ll always be Izuku’s friend. We’re going to become heroes together.” Deep down, he suspected he hadn’t been a very good friend lately, but he could still promise that much. He’d never, ever give up on his future hero partner.

Mr. Midoriya grunted. Katsuki had the odd feeling that he’d disappointed the adult. That didn’t make sense. Surely Izuku’s own father wouldn’t turn on him like the teachers at school? Mr. Midoriya was scary, but he doted on Izuku. He always purchased any All Might merchandise that Izuku wanted, even though his face pinched in a funny way. Now his face looked like a storm cloud.

Katsuki looked down and shuffled leaves with his feet. He was starting to feel scared, but he couldn’t put his finger on why. Just something dark in the air.

Mr. Midoriya sat down on the sidewalk bench. “I have something to show you.”

“Is it All Might merchandise?” Katsuki asked.

Mr. Midoriya sneered. “Something far better.”

Katsuki was curious enough to take a seat. Mr. Midoriya always brought back the best presents for Izuku from his business trips. The man might have the stare of a villain, but he had great taste.

Mr. Midoriya held out his hand. A ball of light formed on his palm. “Watch the light.”

The pale sphere flickered, turning yellow, then green, then dark blue, before returning to pure white.

“This is boring,” Katsuki said.

“Keep watching. You’ll see something special.” Mr. Midoriya smiled in a way that was exactly like Izuku when he had a fun surprise in mind.

Katsuki was curious. He stared at the light as it repeated its pattern of flashes.

“Relax,” Mr. Midoriya said. “Breathe deeply.”

Katsuki felt a wave of relaxation go straight to his bones. His shoulders sagged. His head nodded forward. His arms hung uselessly at his side, like a puppet with severed strings.

Mr. Midoriya hmmed with satisfaction. “Keep taking long, slow breaths. Feel the air course through your lungs. When the air leaves your body, so do all your cares. Watch the light.”

Katsuki no longer had a choice. He couldn’t look away from the glowing sphere. He couldn’t even blink. Something was wrong. But this thought didn’t bother him. It was just a distant irritation compared to the flow of calmness. Though he tried to focus, his thoughts slipped away as if gently tumbling down a hill.

Mr. Midoriya was speaking, but Katsuki couldn’t understand the words. He just knew they sounded beautiful, like a lullaby. They dripped into his mind like the sweetest honey.

When Katsuki returned to awareness, he was sitting on his bed at home. He didn’t remember how he’d gotten there. But he felt tired. He went to sleep.


The next morning, Katsuki felt refreshed. As usual, the other boys gathered around him before class started and talked about a cartoon show. Izuku didn’t try to approach them.

Watching Izuku sit alone in his seat and scribble in his notebook, Katsuki felt a sick twisting in his stomach. With his shoulders hunched over, Izuku looked sad and lonely.

Glancing at Izuku, Tsubasa snickered. “He’s so creepy. Listen to him muttering.”

Katsuki felt a surge of anger. He would bet that whatever Izuku was muttering was far more interesting than Tsubasa’s boring blather.

His temper snapped. Katsuki pushed back his chair and stood up. He was going to talk to Izuku. He’d gotten fed up with wasting his valuable time entertaining stupid extras. He didn’t care if the other kids started ostracizing him too. (He did care, so much that his hands shook and his heart flip-flopped.) He’d made up his mind. He would stick with his only true friend—

Light flashed across Katsuki’s vision. He heard a click, like a door opening.

Blink. Katsuki returned to awareness. He glimpsed his reflection in the classroom window. His face looked slack and blank. He could barely recognize himself. When had he walked over here?

Distantly, Katsuki heard screaming. He looked down. Izuku was rolling around on the floor. His clothes were on fire.

Katsuki tried to reach down. A teacher shoved him out of the way. Shouting. Chaos. Katsuki had trouble believing this was real. He closed his eyes, and it all faded away.


Mitsuki Bakugo hung up the phone, then whirled on Katsuki with a fury in her eyes that he’d never seen before. “My best friend won’t even talk to me any longer because of you! How could you attack Izuku like that, you shitty brat? He had to have skin grafts!”

Katsuki burst into tears. “I-I didn’t,” he said between sobs. “I wouldn’t have—I only wanted to talk to him—I would never have hurt him like that! We’re friends!”

Mitsuki growled low in the back of her throat. “Losing control of your quirk is no excuse.” She ground her fist into the top of his head. “You shouldn’t have been exploding anything at school at all!”

“But I didn’t!” Katsuki wailed. “I didn’t do anything! Izuku was already on fire when I opened my eyes! Someone else must have done it! Everyone hates Izuku because he doesn’t have a quirk. They probably blamed it on me because I still tried to be friends with him.”

“Oh, a likely story.” Mitsuki ground down even harder.

“Stop.” Masaru stood up and grabbed his wife’s wrist.

She looked up in surprise. Katsuki even stopped crying. This was completely unlike his always passive father.

Masaru said, “You know our boy, Mitsuki. He’s terrible at lying. He never cries, not even that one time he fell off the swings and broke his arm. The only time that Katsuki cries is when he’s been unfairly accused of something that he didn’t do.”

Mitsuki swallowed. “That’s true,” she admitted in a subdued voice. “He’s never been able to tolerate unfairness, not since he was old enough to know what the word meant.”

Masaru knelt down and looked Katsuki in the eyes. “You didn’t burn Izuku?”

“I didn’t,” Katsuki said with total sincerity. He never would have done such a thing.

“I believe you.” Masaru brushed his hair out of his eyes.

But even though his parents believed him, Katsuki was never invited to the Midoriya house ever again.


Katsuki approached Izuku at school several times. He wanted to settle the misunderstanding. But every time Katsuki tried to talk to Izuku, he heard another click inside his head. And then he didn’t remember what happened afterward. But Izuku always seemed scared and bruised when he returned to awareness. Katsuki kept getting in trouble. The teachers didn’t do much, just told him to play less roughly with a quirkless boy. But if this continued, if his parents found out, then they might stop believing him. Katsuki couldn’t bear that.

He gave up. He avoided Izuku, and the feeling was mutual.


At age fourteen, Katsuki was sick and tired of being in the same school as fucking Izuku Midoriya. The same class, even! Whenever he was around shitty Deku, he kept losing time, then getting in trouble. He didn’t care if it was fair or not to blame the nerd. He just wanted it to fucking stop.

Any contact with Izuku could set it off. Accidentally meeting those big, innocent green eyes. Hearing the nerd’s fucking obnoxious voice. If only Deku would stop muttering, maybe Katsuki wouldn’t keep getting such terrible headaches. The ones that caused him to blackout. Katsuki couldn’t tell anyone about shitty blackouts. The one time he’d tried, he’d just lost memories again. The words refused to be spoken. Besides, if it went on his record that he was crazy, then how would he ever get into U.A.?

As long as he wasn’t around fucking Deku, he was normal. Katsuki clung to the knowledge that soon he’d be at U.A., where a quirkless twerp couldn’t possibly follow him. Then they’d both be better off. It made Katsuki feel horrible guilty to see that pathetic look on Deku’s dumbass face. He knew he kept doing bad things. He couldn’t stop. Once he’d come out of a trance with scraps of Deku’s beloved notebooks on his hands, then he’d gone to the bathroom to throw up.

Less than a year left of middle school. Then he could finally fucking escape this living hell.

Katsuki slouched home from school after another day where he’d forgotten way too much. His head throbbed.

“Kacchan!” Izuku waved at him from the end of the alleyway.

Huh? When had Katsuki taken a pointless detour into some shitty, smelly, deserted alleyway? And why was Deku giving him that maniac grin?

Katsuki grunted and tried to walk past the nerd. “Fuck off.”

Izuku grabbed his arm. “But I need your help, Kacchan.”

Katsuki flinched. Not fear for himself, but fear of how many times he’d blacked out and come back to find Izuku injured. He jerked away. Didn’t the goddamn nerd have any survival instinct? “Leave me alone, shithead.”

Izuku giggled. “I need your help to get All Might’s quirk.”

Katsuki stared. It was official. The nerd had finally lost it.

Izuku continued, “Dad needs that quirk. He’s given me so many gifts, I want to give him one in return. Call it an early Father’s Day present.” Izuku’s grin became even less sane, if that was possible. “I thought All Might would give it to me if I said I was quirkless and wanted to become a hero, but that wasn’t good enough. I’m going to rescue you so he’ll see me as a true hero.” Izuku clapped his hands. “It will be just like the hero and villain games we used to play as kids, back when you wanted to be my friend.” Izuku’s voice was sharp and brittle.

Katsuki flinched away from the raw pain he saw in those green eyes. “We’re not friends any longer.” It had to be like that. “Give up the fucking fantasies.”

“Aw, but Dad promised that you’d become my friend again.” Izuku pouted. “Dad wanted to kill you. Something about you being distantly related to someone he hates. I wouldn’t let him. After all, the two of us promised to be villains together when we grew up! I told Dad that if I gave him One for All, the ultimate piece of All Might merchandise, then I ought to get something in return. So he agreed to let me keep you.”

Katsuki backed away. “I’d never become a villain. That wasn’t what we promised when we were kids, you dumbass.”

“Dad taught me how to make you into my friend again.” Izuku held out his hand. A glowing sphere formed on it. “Watch the light.”

Katsuki’s body went slack before he had time to scream.


Katsuki woke up in the Sludge Villain’s grip. Then he screamed and screamed, but no one came to save him. Not until Izuku.

Something was wrong. Katsuki had to tell All Might that something was wrong. This was all part of a plan to steal something from All Might, he almost remembered it. But his body wasn’t working. His mouth felt like someone had stuffed it with tar. He couldn’t speak.

As they loaded Katsuki into the ambulance, Izuku winked at him. “I knew you wouldn’t mind if I used you. Because we’re friends.”


Katsuki stood still as Izuku helped him put on his jacket. It was jet black with a red “X” across the front. Next, Izuku fastened on the red gauntlets. Then he placed a black mask with white teeth drawn on it over Katsuki’s face. Steering him toward the mirror, Izuku asked, “How do you like your debut costume, Kacchan?”

The reflection staring back at Katsuki was terrifyingly evil. It reminded him of all the villains he’d watched on the news. Something scraped at the back of his mind, a distant memory of watching an All Might video as a child. He’d wanted to be All Might. Or maybe beat All Might. He no longer remembered.

Izuku looked equally sleek in a green shirt with a black vest, black gloves, and knives strapped to his belt. They looked like a pair of villains. Villains? Katsuki blinked. He asked, “Weren’t we going to become heroes together?”

Izuku laughed. “Of course not, Kacchan! Who would want to become a hero? They’re fake and worthless. We promised to become the greatest villain team, ever since we were little kids.”

Watching in the mirror, Katsuki saw the brief moment when something blank flashed across Izuku’s eyes. He knew that look all too well. He’d seen it on his own face many times, right before he lost his memories. Whirling around, he grabbed Izuku’s shoulders. “No! This is wrong! We’re both being controlled—”

“Aw, are you getting cold feet about our big debut, Kacchan?” Izuku patted his cheek. “Don’t worry. I know how to calm you down. Dad always does this to soothe my nerves.” Light flashed in Izuku’s hand.

Immediately, Katsuki’s face relaxed. His thoughts became distant. He felt calm and content. He was going to become a villain alongside his childhood friend, just like they’d always promised each other.

“Thank you.” Katsuki smiled, sincerely happy. “You never gave up on our dream, and you never gave up on me. Now that we’re together again, nothing can stop us.”

Izuku hugged him. “Of course I’d never give up on you. We’re friends.”

Katsuki followed Izuku out of the building, toward U.S.J.

Notes:

I wrote this fic for HopelessBear’s brainwashed BNHA characters contest. Actually, my initial plan was to tell a story about Evil Izuku brainwashing Katsuki to bully him, so he could manipulate All Might into giving him One for All for his father. But as I started writing it, I felt uncomfortably like I was victim-blaming Izuku for his own bullying. So I scrapped the idea and made Izuku brainwashed, too. I had no discomfort with making All for One an even shittier person than usual (and that’s saying something).

Hisashi used Tsubasa (Dr. Garaki’s adopted grandson) to start the bullying because he wanted Izuku to give up on being a hero and join him willingly. It didn’t work, not even after he brainwashed Katsuki. Izuku kept stubbornly clinging to his dream. At some point Hisashi decided to screw it and brainwashed Izuku after all. Then he came up with a plan to steal One for All, because by Jove he was going to salvage something out fourteen years of purchasing hero merchandise. Hisashi would have preferred to kill Katsuki, since he’s a distant descendant of Second’s family. But Villain Katsuki was a compensation present for Izuku, like the All Might merchandise that Hisashi only buys for his son’s sake.

Even though I like to write Dad for One fics where All for One finds out about his son’s bullying and gets overprotective, I wouldn’t put it past canon All for One to let his kid be bullied in order to turn him against society. Also, if All for One had a hypnosis quirk then he would absolutely use it on all his relatives, everyone living in the same neighborhood, One for All holder descendants, the HPSC, Japan’s politicians, passing pigeons, etc.

Edited to add: azzabynes drew beautiful fanart for this fic. It's haunting, there's a second version of the art at https://www.tumblr.com/azzabynes/734208127082414081/two-versions-of-my-fanart-for

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