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Zero: The Birth of the World's Best Hero Duo

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Katsuki dug into his lunch, trying to ignore his classmates. Stupid Rabbit Teeth kept poking him though, and asking him what his parents did. Apparently the idiots had already answered her. Now she wanted to know about him and Zuku.

He glared at her. "My Dad and Mom both do fashion stuff. It's stupid." Katsuki bit off a chunk of onigiri and ignored the girls squealing. Stupid girls always loved clothes. It was weird.

"That's so cool! You always have cool clothes, Bakugou." Rabbit Teeth grinned at him. He glared back. He didn't like clothes. He also didn’t like her. She was nosey. Maybe he should call her nose girl instead. The girl frowned, then turned to Zuku. "So Midoriya, what do your Mom and Dad do?"

Katsuki's hands clenched around his chopsticks. How dare Rabbit Teeth ask Zuku that?? Dumbass girl couldn't figure shit out.

"Um..." Zuku was looking down, staring at the table. He poked his pork with a chopstick. "My Mom's a nurse."

"That's neat! She must help a lot of people." Rabbit Teeth was grinning. Damn idiot not noticing Zuku was upset. "What about your Dad?"

Zuku winced.

Katsuki's chair clattered to the ground. He glared at Rabbit Teeth. "Shut up! Don't ask him that!"

"Your hands!" Big Nose was staring at him, his hand shaking and pointing at Katsuki. "They're smoking!"

Katsuki stared at the thin smoke. He opened his fist. It was… coming from his palm?

His quirk had come?

"Kacchan!! That's amazing!" Zuku grabbed his hand, pulling it closer to him. He stared at the smoke. "You're so amazing, Kacchan!" Zuku's smile was back.

Katsuki smirked. "Of course I'm amazing."

Zuku's head was still nodding up and down. "When a quirk first shows up as smoke, that means it usually has fire. So you'll have fire in your hands, Kacchan! It's awesome! So cool!"

Fire? Hell yeah! Fire was the best! Of course he'd get fire! Maybe Zuku would have fire too? His idiot jerk of a father could breathe fire, so it would make sense. They'd be an awesome fire team!

Katsuki stared at his palm. The smoke was gone, now. But it had been there.

Just a little more waiting. Then he'd have his fire.

And then Zuku’d get his quirk.

It took a month. A whole long ass month. And then, when he was yelling at his mom, suddenly there was a small pop from his hands.

Then another.

Katsuki’s eyes widened. He stared at his hands, argument forgotten.

His quirk wasn’t fire.

It was explosions.

Katsuki grinned.

This was the best fucking day ever.


“Kacchan?” Katsuki glanced over from the TV to where his soulmate was scribbling in that same shitty notebook.

“What, nerd?”

“I’ve… I’ve thought of some things for your quirk.” Zuku was scratching his head with a pencil.

“For my quirk?” What the hell? It had only been a week since the explosion. Had the idiot been thinking about nothing else?

“Yeah!” Zuku bit his lip, unsure, then took a deep breath. “Like, have you ever thought that maybe you could make explosions somewhere else? Not just your hands? Or like, maybe you could explode yourself and force the air down, you know, so it would push you up? It’d be really cool if you could fly like that! Or maybe you could like, store sweat somehow? It’s hard for you when you’re cold, right? Or you—”

“Zuku!” His soulmate froze, mouth still opened wide. “Is that what you’ve been writing about?” The nerd had been glued to the book all week. AND he’d refused to tell Katsuki anything about it. The damn brat.

Now, though, Zuku just nodded and scooted toward him before shoving the notebook into Katsuki’s hands. A rough drawing of Katsuki was on one side. The other one was a bunch of details about his quirk. And a lot of questions under those details. Huh. He reached his arm around Zuku’s neck, pulling him down so that he could rub his head with his fist playfully. Zuku flailed.

“Kacchan!! Mercy!”

“You shitty nerd. How’d you think of all this?”

“I just want to help, Kacchan!”

He released Zuku and the boy collapsed on his lap like a noodle. Katsuki shoved him off onto the ground. “Come on. Let’s go to the park and see if any of it works.”

“Yes, Kacchan!” Zuku hopped up, grinning from ear to ear. Katsuki headed toward the door. He raised his voice to call out, “Auntie, Old Hag, we’re going to the park!” He reached the front door and slipped on his shoes. His mouth twitched when he noticed Zuku’s hands were empty. “Don’t forget your scribbles, Zuku.”

“Right!” Zuku scrambled out of the room. Katsuki rolled his eyes. Sheesh, he really did have to do everything.

Even after the run to the park, Zuku was still bouncing up and down in excitement. Idiot. It was Katsuki’s quirk, not his.

“You sweating yet, Kacchan?”

He sighed and nodded. That was one thing he’d noticed already—he was sweating a lot easier than he used to. He supposed it was good, though.

“Awesome!” Zuku’s eyes were big and he grinned at him. “Can you make some of it explode? But not all?”

Katsuki frowned. He didn’t know, but he could try. Maybe if he tried just one side of his hand?

He flexed his hand, and all the sweat droplets blew up.

Katsuki groaned.

He turned to his other hand while he waited for sweat to gather on his right one again. He focused on the feeling he’d had when the sweat exploded, trying to make that happen just to the left side of his hand—

Was it just him, or was the explosion on the right side a bit weaker, that time?

Zuku was staring at his hands intensely but hadn’t said anything. Katsuki frowned. It must’ve been the same.

He wiped his forehead, gathering more sweat. And then he tried again.

And again.

And again.

And again.

After the gazillionth try, he was beginning to think it was impossible. “Zuku, maybe we should—"

“I really think you can do this, Kacchan!” He stared at Zuku’s determined eyes. What the fuck? How would he know? It wasn’t his quirk.

“It’s been getting weaker! Just keep going!”

“It’s been getting weaker because I’m fucking tired, Zuku.”

“Still! One more!”

Katsuki sighed, this time sticking his hand in his armpit. He felt a bit lightheaded.

One last try.

His palm lit up, but he stopped it quickly, exhausted.

He stared at the beads of sweat.

There were still beads of sweat.

He hadn’t exploded it all.

His wide eyes met Zuku’s.

It was timing! He had to control how long the explosion went, not what part of his hand he used!

He tackled Zuku, laughing. The two of them fell to the earth. “Nice going, nerd.” He took a deep breath. He felt like the world was spinning. “We can try the rest some other time.”

“Of course!” Zuku was sitting up, grinning at him. “Come on, Kacchan! Let’s go home!” He stood up and held out his hand.

Katsuki reached up to grab it but missed. The world spun again. His hand fell uselessly to the ground.

Zuku frowned, “Kacchan?”

He groaned. He really didn’t feel so good. Katsuki rolled to his side.

Then he threw up on the grass.


Zuku’s hands were on his shoulders, sitting him up. “Kacchan, are you ok?!” Katsuki could hear the fucking tears. He slowly stood up, weaving slightly. “Kacchan, I’m so sorry! You said you were tired, we should have stopped, you must have pushed yourself too hard…. I know it’s dangerous to practice your quirk on your own, but I was here and you weren’t alone and I was just so excited and you were excited and—”

“Zuku.” Katsuki held onto his soulmate’s shoulder, trying to keep the world from swaying. “Home.”

“Right! Of course, Kacchan!”

The walk home was slow. Katsuki hated that he had to stop so much, but they made it.

Auntie took one look at him and was by his side, pushing her own son away. “Katsu-kun! Katsu-kun what happened?”

He closed his eyes, trying to ignore the dizziness and the headache. “Was practicing my quirk. And then I got… dizzy. Really dizzy. And I threw up. And my head hurts a whole fucking lot, Auntie.”

“Oh Katsu-kun.” Auntie’s arms wrapped around him. “Izuku, dear, go get some water for Katsuki, please.”

Zuku ran off, fast. Katsuki wanted to laugh at the nerd’s sudden speed, but he was confused. “Water?” What was wrong with him?

“You’re dehydrated, Katsu-kun. It means your body doesn’t have enough water. Where do you think all that sweat came from?” Aunty patted his shoulder, “It’s easy to fix, though, don’t worry. But you have to drink a whole lot whenever you use your quirk, alright?” She gave him a stern look. Well, a stern look for a Midoriya. “Or this will happen again.”

Zuku was back with the water, and Katsuki grabbed the cup. His hand was shaking. His hand was fucking shaking.

He took a big gulp of water. It tasted so good. He went for another, but Auntie’s hand stopped him. “Slowly, Katsuki, or you’ll throw up again.”

Shit, he didn’t want that.

Katsuki slowly sipped at the water, letting Aunty hold onto him until he finished the cup.

“Feeling better?” Katsuki nodded. Auntie passed the cup back to Zuku, who ran to the kitchen. Nerd was probably getting more. “Let’s get you to the couch, then. Drink some more water and take it easy for the day, you hear me young man? Your quirk doesn’t make you invincible.”

Katsuki frowned. Invincible?

Zuku was back, handing him the cup. “Invincible is like heroes! They can’t be beaten!”

“I knew that, shitty nerd.”

“Uh-huh. Sure, Kacchan.”

Katsuki glared at him but drank the water. His hand gripped the cup, hard. He wouldn’t do this again. Be this weak. He’d practice a lot. A whole damn fucking lot. And one day, he and Zuku would be invincible.