Chapter Text
Izuku learned early on in life that not all men are created equal.
He definitely didn't have it as bad as other people. His quirk may have been useless, but it wasn't like he didn't have a quirk at all.
When Izuku was born, there had been a lot of confusion, seeing as the baby his mother had given birth to didn't have a set of human ears on each side of his head. No, atop his head was a set of furry ears, and a tail sticking out from his tailbone.
The doctors had taken it in stride, though his mother had been confused as to where those traits had come from. With her minor telekinesis quirk, and his father's fire breath, shouldn't he have had some combination of the two?
Turns out, genetics were weird. Unbeknownst to his mother, his father's extended family had had some latent and minor mutation quirks. One of those mutations was what altered his father's throat, allowing him to breathe fire as if he were a dragon.
Unfortunately for Izuku, he'd received part of his quirk from his great aunt, who had a cat mutation quirk, and his mother's 2nd cousin, who'd had a transformative quirk that worked on objects.
Honestly, he would have preferred if his quirk turned objects into cats.
But no, it turned him into a cat.
Among the fuzzy ears and tail, he had slit pupils, claws, fangs, only four toes on each foot, and an obnoxious set of animalistic instincts. Thankfully, at least his hearing, sense of smell, and reaction time were all enhanced. Not to mention that he could talk to cats and understand them perfectly.
And at least he was quite cute as a kid. His big eyes and perked up ears had earned him quite a few pieces of candy when he was young.
Though, there was one major drawback.
He was a common house cat. Not something cool, like a leopard or a tiger. Just a regular, domestic house cat. A black cat, specifically, though his fur contained dark patches of green, much like his hair in his human form.
And when Izuku fell asleep, his body didn't maintain his human form. As soon as consciousness slipped away from him, his body took on the form of a tiny, black cat. He had a theory that it was his body's natural way of conserving energy, deeming it easier to restore his full energy as a tiny feline rather than a full grown human boy.
It was very inconvenient as a kid— seeing as he had no control over his transformations back then, leading him to end up in precarious situations as a defenseless kitten.
The day the transformation aspect of his quirk had showed up at four years old… it had been a hell of a ride.
He'd gotten his quirk before Kacchan (something he was still thankful for to this day as the boy hadn't developed any signs of what the power of his quirk would do to his ego) and had suddenly shrunk one day in the middle of playtime during preschool.
There had been kids running all around the classroom; he and Kacchan had been sitting together, playing with All Might figurines and debating which of his United States smashes were cooler. (Izuku thought his Detroit Smash was awesome, but Kacchan argued that Texas Smash was cooler because it made things explode into tiny pieces.)
A kid had snuck up on them, grabbing his shoulder and scaring the living daylights out of him. He had jumped and—
—was much smaller when he went back down.
He looked around, then down, where tiny paws replaced tiny toddler hands. Everything looked so big, so daunting to what was now a tiny green and black kitten with wide emerald eyes.
Suddenly there was yelling, and there were tiny preschooler hands grabbing at him. He thrashed and whined in their grasp, lowering his head and biting the unfamiliar fingers gripping his fur. There was a sharp, squeaky yelp, and he landed on his feet on the floor. He looked around, finding that everyone was staring at him— some people were yelling, some were gasping, some looked disturbed at the sudden disappearance of their already vaguely cat-like classmate and appearance of a tiny full-blooded feline in his place.
His eyes locked onto the one safe thing he could trust: Kacchan, staring at him with wide, unsure eyes. He ran to the boy, jumping at him. Kacchan gasped, catching the kitten and holding him in his arms, looking down at him in a mix of confusion and slight awe.
"…Izuku? What happened to you?" He asked in an uncertain voice. A tiny, distressed mewl escaped Izuku as their teacher arrived and tried to grab him. He sunk his tiny claws into Kacchan's shirt, thankfully the boy's skin had not been included in his grasp, and pressed his face into the small boy's chest.
Kacchan blinked, then seemed to settle on something. He clutched Izuku to his chest and looked up at the teacher, shaking his head. "Hey, hands off! Are you stupid? Can't you see he's scared!?" He said, pressing the kitten closer.
The teacher took a small step back, saying something that Izuku didn't have the mental bandwidth to pay attention to.
Kacchan looked down at him, carefully prying Izuku's claws out of his shirt.
"Hey, calm down, dummy. Everything's fine, because I'm here!"
Despite the residual panic Izuku was feeling, he huffed quietly in amusement. Of course Kacchan had quoted All Might when trying to calm him down. It had worked too, because he felt his ears, which he hadn't realized were pinned back in distress, slowly perk up. He lifted his head, nuzzling his nose against the other boy's cheek, which sent a bright flush throughout his face.
"Y-yeah, yeah. You can thank me later." He mumbled, but he didn't pull the kitten away.
Instead, Kacchan sat down, holding Izuku in his lap.
"Sensei is letting Auntie know. I think she's gonna come pick you up." Kacchan mumbled, patting Izuku's head. "Can you understand me?"
Izuku nodded his tiny head, and a small smile appeared on Kacchan's face. "Huh. Cool."
Kacchan continued to hold him in his lap, fighting back prying eyes and unwanted touches with glares and harsh words.
When his mom arrived, Izuku gave Kacchan's hand a small bump with his nose and a tiny lick before he leapt out of Kacchan's lap and straight to his mother, crashing into her legs with a quiet mewl. Her eyes widened into saucers in shock, but she quickly composed her expression.
"Oh, baby… When your teacher called saying your quirk had manifested, I wasn't sure what she meant, but…"
Izuku let out a quiet yowl, and she scooped him up into her arms. "Hey, hey, it's okay, honey. It's okay. We're gonna figure this out, alright?" She murmured softly.
She looked up at his teacher and gave her a quiet thank you for calling, then turned to Kacchan. She walked over to the boy and knelt down.
"Katsuki-kun, thank you for taking care of him while I drove here. It means a lot to me that Izukkun has someone watching out for him." She said with a soft smile.
Kacchan blushed and nodded. "O-Obviously I was gonna take care of him. Someone needs to watch over the nerd when you're not around."
Inko chuckled, shifting her gentle hold on Izuku to reach out with one hand and ruffle Kacchan's hair, to which the boy let out an affronted squawk of protest. She smiled a little more and stood up, nodding once again to his teacher and leaving the classroom.
On the way to the car, she looked down at the tiny kitten in her arms. "I can't hold you while I drive— I have a blanket in the front seat that I'm going to wrap you up in, okay? You'll be safe. Do you know where your clothes went?"
Izuku paused, realizing that, no, he had absolutely no clue where his clothes had gone. Thus, he shook his head.
Inko let out a quiet, but not exasperated, sigh.
"That's okay. Hopefully they'll be there when you change back, yeah?" She said with a slightly amused smile.
Izuku changed back on the drive to the quirk doctor, his body slowly growing bigger and taking shape until he was back in his semi-feline, but mostly human form. Thankfully, he was fully clothed.
Inko's eyes widened and she pulled over, taking him out of the front seat and putting him into the backseat. She wasn't going to let a four year old sit in the front seat— she respected car safety laws and wouldn't be taking any chances.
After the doctor had set him down, taken a very small blood test that Izuku had looked away for, while tightly clutching his mother's hand— and Izuku giving the general rundown of the situation along with his mother's description of the call with his teacher— they were given an answer.
"Alright, It seems the mutation aspect of Izuku's quirk was preliminary to his actual, full quirk. Izuku's full quirk is actually a transformative type— It seems he can shift his body into a black cat at will, and when startled or distressed. Seeing as he's so young, he obviously has little control over his quirk. Rest assured, I'm sure that when he's older he'll have almost full control over his shifts." The doctor said with a warm smile.
Izuku looked down at his hands, fiddling with his clawed fingers. That was cool, he supposed. He wasn't sure how many uses being a simple house cat would have if he was gonna be a hero, but that was okay! He would figure it out for sure! He wasn't going to let something stupid like a quirk get in his way.
For most of their youth, from the ages 4-8, Kacchan had acted as his wall of defense, taking his position as Izuku's protector very seriously. Even after he'd gotten his quirk— explosions, so cool!!— he had stepped in in front of bullies and discriminatory adults.
But something in his eyes changed after Izuku had offered to pull him out of that river— and kids talked, and talked, and eventually their whispers began to get to him.
Deku has a worthless quirk— it makes him a target. He really lives up to his name— Why do you protect him like that?
You wanna be hero partners? Hah! What's a tiny housecat gonna do against a villain?
Don't you see how he acts? Purring and meowing? Didn't he rub his face all over your hand one time? It's weird…
Didn't he bring his mom a dead bird in elementary school? It's freaking gross! What kind of person does that? It's psychotic!
He doesn't act like a human should… It's like he's fully an animal or something…
He hissed at me one time! Who the hell hisses at people!?
Why is he always scribbling in those notebooks? I heard he writes all about people like some kind of stalker— it's creepy!
He's always mumbling under his breath— it kind of freaks me out…
He's a freak.
So, yeah, kids talked. A few adults, too. Teachers under their breath, his classmates' parents, his mother's friends.
At least his mother still had Auntie Mitsuki and Uncle Masaru. He knew they would never turn their back on his mom— They'd been friends forever!
But Kacchan…
Izuku knew something was off from the first second that a kid had pushed him down on the playground, and Kacchan had hesitated.
He didn't step in. He didn't defend him. Once the kid had gotten sick of taunting him, snickering something about him being a crybaby and walking away, Kacchan had quietly walked over and offered him a hand up. Izuku had taken it, and asked him why he hadn't done anything.
"You need to learn how to fight for yourself, stupid Deku. You're weak, just like your quirk." He'd said, but it was clear his heart wasn't with the words. They seemed forced, his eyes uncertain. But he'd still said them, and more tears had sprung into the smaller boy's eyes.
He sniffled, mumbling a quiet: "I'm sorry, I didn't mean to be a burden, Kacchan. I'm sorry." His ears were flattened to his head, his tail swishing anxiously back and forth.
Kacchan had bit his lip, looking torn between taking back his words, hugging Izuku, and never letting go, or turning away and leaving him be.
Much to Izuku's despair, Kacchan chose the latter option.
With deep turmoil in his expression, Kacchan cleared his throat, huffed, and turned around. "Whatever, loser…" And the blonde boy ran off without another word.
Izuku could feel eyes on him as tears dripped down his cheeks. He roughly scrubbed the droplets away with the heels of his palms and walked away in the opposite direction.
After school, walking in the form of a small kitten, Izuku wandered the streets. Mom was working a late shift— she didn’t know he was out here.
It didn’t really matter though, no one would notice a tiny kitten scurrying around, hiding behind pots and in the shadows of alley ways.
And he was right, no human noticed him.
But as a large tabby cat walked out of an alley, eyes locking onto him, his blood ran cold.
The cat darted over to him, picking him up by his scruff before he could flee.
But the cat didn’t hurt him, didn’t do anything for imposing on her territory.
Instead, she asked,
”Kitten, where is your mother?”