Instinct

The fact that Izuku Midoriya was in no way unique was, itself, what made him very special. This was a fact that was true from birth, though it only showed itself shortly after the boy's fourth birthday, when science proved beyond the shadow of a doubt that Izuku Midoriya was completely and utterly uninteresting. He did not develop a Quirk, a strange genetic mutation that gave him some bizarre ability. He couldn't run faster than a normal boy, or reach higher, or fly, or project explosions from his hand.

He was totally and utterly normal. And he hated it with a passion. He denied it at first, beside his mother. What a pair they made, a meek young boy smaller than his years and his mother, equally petite, declaring with growing desperation that a doctor who specialized in exactly the sort of thing he was testing for was in fact wrong and Izuku 'did' have a Quirk. The doctor, a tired old fellow well-past his prime, simply shook his head and sighed. He was correct. Izuku Midoriya was one-hundred percent Quirkless.

The boy fell silent, staring at the floor. The doctor knew what was wrong; the Quirkless were looked down upon in modern society. Not outright ostracized, but they had a higher suicide rate than any other demographic by far, and that wasn't some random number. Every year, the number of newborn Quirkless shrank, and the number of older Quirkless who chose to take their own lives rather than live in a world where they were perpetually viewed as lesser, as defective or even as freaks… that number rose. The doctor hoped against hope this boy wouldn't be a part of that rising statistic.

Then the boy looked up, tears brimming in the corners of his verdant green eyes, and asked with a quavering voice if he could still be a hero. The doctor wasn't even sure it was a question directed at him, or just the world in general. The doctor swallowed. His sister had been a hero. A good one at that. But her Quirk, which gave her the ability to sense all motion in a three-hundred-sixty degree radius… that hadn't been enough to keep her alive in the face of the world's more dangerous villains. The funeral had been years ago, but it still hurt to think of her.

A sudden urge overcame the doctor. He hated himself for it, because he was not the sort to go around casually crushing other people's dreams… but he couldn't let this boy kill himself, even by proxy as a hero. Without a Quirk… the doctor swallowed hard.

"You should probably give it up, kid." he said, cursing himself in his head for how dismissive his voice sounded.

The cursing only got louder when the boy, faced with the official medical opinion that heroism was likely impossible, broke down completely and began to cry deeply. His sobs filled the office space and the doctor swallowed even harder, looking away. The boy's mother held him close, crying right along with her son, proclaiming that she was sorry. The doctor recalled that the parents of Quirkless children tended to blame themselves for their children's supposedly 'defective' nature. For a moment he considered reaching out to put a hand on the woman's shoulder… but he pulled away. This was a moment between mother and son. A private moment to grieve what could have been but now would never be.

What could have been…

That night, long after the Midoriya family had left his clinic and right before he closed up for the night, the doctor made a call. It was a shot in the dark, using an old number he hadn't dialed in ages, but he let it ring and ring. After almost half a minute of expectation, somebody picked up.

"This is Doctor Kakure…" he began, taking a long, bracing breath. "I… I've found one."

"Quirkless?" The voice on the other end of the phone was a throaty whisper, a dry and rasping voice, menacing enough to make the doctor's hair stand up on end even over the phone. "You're certain?"

"Y-yes." the doctor replied, nodding. "A boy, age four. Name of Izuku Midoriya. He… he wanted to be a hero."

"Interesting…" the voice said, drawing out the last sound. "You told him otherwise."

The doctor winced despite himself.

"I did." he confirmed.

"Izuku Midoriya…" the voice tested the name. It sounded fundamentally wrong being spoken by that horrifying whisper. "Most interesting… I will inform my Sensei. He will know what to do with that name. Thank you, Doctor. However can we repay you?"

"N-no need." The doctor was no fool; he knew what accepting a reward from these men meant. "C-consider it a free tip. A gift."

"I see…" Once again the voice dragged out the end of a word, before a hoarse chuckle cut its own words off. "Thank you again, Doctor. We will be in touch."

The voice hung up before the doctor could protest. The man let his hand fall from his ear, dropping his phone on the tiled floor. He felt as though he needed a long sleep, in a locked room. His knees shook, despite his subconscious commands for stability. He took a long, gasping breath, and bent down to pick up his phone.

Whether he had just saved Izuku Midoriya or consigned the boy to an early death, he could not say. But… that desperate gasp, that weak little question asked of the wider world… his sister's frowning face flashed in his mind and he put a hand to his forehead. After her Quirk had first developed and she had learned she would be wearing sunglasses for the rest of her life to hide her discoloured eyes that could not see, she had asked him the very same question.

"Can I be a hero?"

The doctor had said yes. His sister had died. In a way, it was his fault. Now...now he may have killed another child, another dreamer with delusions of heroism. The doctor sat heavily in his chair, falling into it, and put his head in his hands. Quirkless suicide rates flashed through his head. The number of pro heroes killed each year. Two very large numbers in context. Damned if he did, damned if he did not.

"You can't be a hero…" he spoke the words aloud, eyes closed. "But... "

The doctor sighed.

"Perhaps HE can make you one."

[X][X][X][X][X]

Natsuki Bakugou's life changed the day her former best friend disappeared from the world.

At first she didn't notice. She didn't even care when she did. So the nerd had gotten sick. So what? She had bigger fish to fry, like teaching all the extras in her new Kindergarten class who was boss. The nerd could up and die for all she cared.

She only realized a week later how very wrong she was. A week later, when she overheard her mother on the phone with Izuku's mother, sounding very distraught indeed. As it turned out, Izuku wasn't home sick. Izuku wasn't home at all. He hadn't been in a week, having disappeared into thin air sometime in the night. Straight from his own bedroom; there when Inko had sent him to bed, gone the next morning. His window had been closed, all his clothes in place, his school backpack still on its hook. Even his shoes were still where she had left them.

The nerd had just vanished. And Natsuki, precocious five year old that she was, decided that she was going to find him and teach him a lesson for scaring her aunty Inko like that. She began immediately, at first coming home late from Kindergarten (which was just down the street from her home, and therefore within walking distance for even a five year old) in the name of searching nearby parks. Soon Natsuki realized that to find the nerd, she would have to look further from home.

One disastrous nine-block trek later, she was perhaps the world's first five year old truant and in very, very deep shit with her mother. Mitsuki Bakugou didn't even ask where her daughter had been, instead sending her to her room before calling her husband home from his search with the family car. The two deliberated on how to punish their errant nomad of a daughter for a good hour, only to open her bedroom door to find that she had climbed out the back window, over the backyard fence, and gone hunting for Izuku again.

That particular search took approximately two hours, before she was found trying to interrogate a very confused shopkeeper about Izuku's location. Mitsuki cried for over an hour, before grounding her daughter for a month. And then, after that particular hammer was dropped, she finally decided to ask her delinquent kindergartener daughter why she had run off twice and what on earth she thought she was doing.

The sullen answer of 'looking for stupid Izuku!' was received with a confused stare that slowly descended into even more tears as Natsuki's husband tried to console her. Natsuki, on the other hand, just wanted to go out and look for Izuku again. It took Mitsuki several minutes to explain that Izuku was being looked for by the police, and that there was nothing Natsuki could do.

Natsuki received news of her own helplessness about as well could be expected and, using her Quirk, Explosion, she nearly destroyed a china set formerly belonging to her own grandmother. Once that little tantrum ended, she began to cry for the first time in her own living memory, unable to accept that 'the nerd' had just vanished like that and that there was nothing she could do about it.

It was only a month after that, when the Izuku Midoriya case had been closed due to a lack of any workable evidence or leads, when Natsuki's life changed again. There was a knocking at the door, and her mother answered only to gasp in surprise. When Natsuki poked a head around the corner in curiosity, she too was surprised to see none other than Inko Midoriya, Izuku's mother, standing in the doorway clutching something in her arms.

"H-hello, Mitsuki…" she said, voice frail, like she could break into tears at any moment. "I-I… I have something f-for Natsuki."

Natsuki rounded the corner, walking up beside her mother with a surprising lack of assuredness to her gait. She didn't know what to do with this or how to approach this situation. This was alien to her. Inko looked at her, and then took the thing in her arms, some sort of… notebook? She took it, and held it out toward Natsuki. Her mouth opened to speak, but all that escaped was a quiet squeak, before she sniffled and started to cry.

As her mother wrapped Inko up in a big hug, Natsuki took the book. It was a simple spiral-bound notebook, the cheap sort you bought at an office supply store for a couple hundred yen. Scrawled on the cover in chicken-scratch kanji were a few simple words, and Natsuki's eyes went wide when she read them.

'Hero Analysis for the Future' the title said, 'By Izuku Midoriya'.

Natsuki retreated to her room, her mother and Inko both too focused on each other and Natsuki's newly arrived father's efforts to try and get them to sit down (he had become quite adept at dealing with emotional women in the preceding month) to notice her disappearance. She slammed the door, before throwing herself on her bed and opening the notebook. It was mostly empty when she flipped through it, but the first few pages were chock-full of content… and all of it revolved around her.

'Natsuki Bakugou' read the same sketchy kanji as the front cover '(Naachan).'

Natsuki swallowed and kept reading.

'Quirk Name: Explosion. Naachan's Quirk is super cool! It lets her make explosions with her hand, and she can use them to do all sorts of stuff. She can make little poppy ones like firecrackers, or big explosions, or make an explosion when she punches to make it hit harder! Maybe one day she'll be able to fly with explosions! That would be super cool!'

Natsuki filed that tidbit away for later. The rest of the entry read much the same, with glowing praises of herself, her Quirk and her potential mixed in with fairly impartial observations and ideas for prospective improvements in a troublingly high quantity. Natsuki was astounded by the depth of Izuku's notes, how much love and care he clearly put into her entry. She was the only one in the book; perhaps he had planned on doing more of his favourite heroes. The only other notes were the beginnings of an entry on All Might, on the page right after her's.

Natsuki paused and considered that thought for a moment. Izuku, All Might fanboy that he was, chose to write multiple pages about her and her Quirk before giving so much as a single word to his favourite hero of all time. She flicked back to her entry, noting a sort of postscript-addendum at the bottom of the final page.

'Naachan is super 's super brave and strong and smart, and I just know that one day she'll be stronger than All Might. Her dream is to be the number one hero, and she's definitely gonna do it. She's gonna be the number one hero some day.'

'Naachan is super cool.'

Unbidden, a memory of one of their last days of preschool came to mind. Izuku had looked miserable all day, which had been weird to Natsuki. She thought his momma had taken him to the Quirk doctor, so he could figure out what his Quirk was.

"Hey, Izuku, what's your Quirk?" she had asked, as casually as she could in the middle of the playground, surrounded by other kids.

"I-I… d-d-don't have one, N-Naachan..." He had looked afraid of her, unable to meet her gaze.

"What? What kind of weirdo doesn't have a Quirk?" Such an idea was utterly inconceivable to her childish mind. Everybody had a Quirk, that was just how the world worked!

The other children had interjected at that point, butting heads into their conversation.

"Izuku the weirdo, doesn't even have a Quirk!

"That's super weird, Izuku."

"What're you supposed to do without a Quirk?"

"Man, sucks to be Izuku!"

Izuku had run away that day. And just a few weeks later, he had disappeared. It was… strange, and Natsuki desperately hoped it was a coincidence. But she wasn't so sure, especially not now. She looked over the post-script again, reading deeper into the words there and swallowing hard.

'She's gonna be the number one hero some day.'

Natsuki didn't cry. Not quite. She'd already shed her tears for Izuku. But she did tear up, and take a few deep breaths to stop herself from crying. Crying wasn't of any use. What good would crying do for Izuku? She still needed to find him… no matter what it took. She put that notebook in one of her desk drawers, right underneath her pencils. That way, no matter what… she would see it. Hero Analysis for the Future.

It was her job to make sure Izuku's future came to be.

[X][X][X][X][X]

Natsuki Bakugou spent the next three years of her life improving herself. She did it not out of a sense of pride or a desire to surpass, but instead because she needed to. Because the stronger, faster and smarter she got, the more likely it was she could find Izuku. She blitzed through elementary school, forcing herself to top every class. On the field she was a monster, her body forcibly made strong from the kickback of her Quirk and her refusal to sit still, to always be moving. Her parents watched her grow taller, stronger, until at age eight she was easily the most athletic student in her entire school.

And at age eight her whole life was rocked and reshaped yet again, when she took a right down an alleyway while walking to the store for her mother and nearly tripped over the crumpled form of a person, curled on the cement. She caught herself with a small explosion, the popping sound echoing through the alley, and she heard the figure emit a quiet whimper of fear. Her eyes tracked along it; it was a boy, she figured, from the width of its shoulders and messy but short-ish hair.

Messy green hair.

Natsuki's eyes went wide. Her jaw dropped and then slammed shut a moment later when she crouched down beside the figure that had to be the one person she never expected it to be. She heard that whimper again, the figure shuffling away from her, squirming on the ground. She could see black skin, pitch black, the same colour as a starless night sky. She touched a hand to its shoulder, and shivered at the sheer heat of its skin. She had a natural heat resistance, a minor mutation to protect her from her own Quirk, but this… this was hot. Like, pot-off-the-stove hot. Her touch incited a new reaction from the figure.

It cried out, and Natsuki recoiled. It was an animal sound, a sound of raw terror, before suddenly its arm swung up. It had the dense musculature of a boxer or weightlifter, an open hand shoving her away. She flew, sailing through the air before slamming into the ground almost ten feet away. She clambered to her feet and saw the thing standing. She saw verdant green eyes, now literally luminescent, glowing in the low light. The thing made a sound like a wounded dog, a soft whine, and hunched down, catching itself on its hands and knees.

She took a step forward, hand out. She wanted to look unthreatening, but… she was Natsuki Midoriya. She was an eight year old with the body of a ten year old boy, besides the natural narrowness of her waist and slightly thinner shoulders. Her sandy blonde hair was in its usual violent spikes, her eyes blood red and probably glimmering slightly in the low light. The thing made another fearful sound, backing away from her, crawling.

Natsuki blinked twice, before dropping into a squat.

"Izuku?" she tried.

The thing reacted with a look of something like awe, mixed with terror.

"N-noooo…" it croaked, shaking it's head slowly, backing away. "N-no Zu-Zuku… only N-Nine…"

It's voice was… it was like Izuku's. But it had dropped a few registers, and it sounded like his throat had been lined with sandpaper. But she would no that stutter anywhere, and those eyes, and that hair. This… this was Izuku.

"Izuku… it's me, it's…" In her mind she scrambled for something, anything, before her eyes went wide. "It's Naachan!"

Izuku… Nine… whatever he was… he shuddered. His eyes went wide, the lights within them brightening, and then suddenly he rushed forward on all fours. Natsuki forced herself not to panic and blast him, letting him come. He skidded to a halt right in front of her, wrapping his powerful arms around her legs.

"N-N-Naachaaaaan…" he rasped, the fear fading from his voice. "Naachan… Naachan… Nine sorry…"

Natsuki touched a hand to his head, scruffing that disaster of a haircut. It was wild, tangled, unwashed. She sniffed and then recoiled a little. Izuku stank, bad. It was obvious he hadn't spent much time washing, and all he was wearing was a filthy pair of shorts. Natsuki considered taking him to the hospital, or the police, before her eyes went wide.

She had found Izuku. Holy. Shit. She had found Izuku. She grabbed his head with both hands, as if making sure to anchor him in place, and stared into his eyes. He shifted, fear returning to his features, and she quickly released his head before he panicked again. Instead she imitated her mother and touched a hand to his cheek, which he nuzzled against.

"Naachan…" he said again. "M-m-momma… safe…?"

"Your moms fine, nerd…" Natsuki said, squatting down in front of him. "Come on, let's go see him. Or… call the cops."

Izuku panicked at that suggestion, eyes going wide. He backed away from her just a little, looking all around them as if checking for listening ears or spies or something. It was almost like he was expecting to be surrounded. This revealed his bare torso to Natsuki's eyes, and they too went wide when she saw… holy shit, were those all scars? Two really long ones, like claw-wounds or something, and a bunch of smaller jagged ones, puckered light purple lines on his stomach and chest.

"Izuku… Izuku, what's wrong?" she asked, before glancing over her shoulder. "Is something wrong?"

"N-n-no c-cops, S-Sensei get m-m-mad if c-cops…" Natsuki's stomach ached suddenly as Izuku curled in on himself again, as if trying to hide in the alleyway. "N-no c-cops n-no mad Sensei n-no knives needles hammers… n-no more test…"

Tests? Knives? Hammers? What was Izuku talking about? Where… where the hell had he been? Who was Sensei? All of these were questions Natsuki asked herself as she stealthily grabbed her brand-new cell phone, tapping the three digits for the police before hesitating with her thumb over the call button. Hopefully they would track her phone and come see what was wrong… unless they thought she was a crank caller or something. Oh man, that would be bad. But Izuku was panicking, freaking out at the idea of the only people she could think of to contact. Then she blinked twice.

"Izuku… what if I called a hero?" she chanced, looking at him.

Izuku seemed to sit up straighter at that idea, his eyes meeting hers again, wide with some of that old Izuku excitement. He practically vibrated in place.

"A-a-a Hero…?" Natsuki could almost hear the capitalization. "F-for N-N-Nine?"

"Yeah, a hero…" Natsuki scrambled to remember any local heroes. Death Arms, maybe? Or that newer guy, Backdraft? The latter was a rescue hero, but more of a firefighter or something. Death Arms was probably a better bet, but… well, his name was Death Arms. Would Izuku, this new black-skinned Izuku that seemed afraid of everything, be able to handle someone like that?

Death Arms it was. She dialled the agency, having memorized the number out of boredom, and then stood listening to the dial tone for a minute or so. Izuku sat passively against the wall, not making a sound, just staring at her.

"Death Arms hero agency." a calm woman's voice answered. "Is this an emergency?"

"Um, yes…" Natsuki said, and before the woman could comment on her age, she continued. "I-I found a missing person, Izuku Midoriya? He's… um, he's… been changed."

"Hmmmm…" the woman went silent for a moment, the clatter of a keyboard audible over the phone. "Midoriya… oh my. This case is three years old… are you sure it's him?"

Natsuki looked at Izuku, who was still staring up at her with an expression somewhere between fear and happiness.

"Yes… he's… he was my friend before he…" Natsuki shook her head. "It-it's him. He… he's been… he's been changed. Can you send someone?"

"Death Arms is currently taking care of a bank robbery, but one of his Sidekicks could come by and take a look." the woman offered. "We could also inform the police."

"No!" Natsuki protested, before looking at a startled Izuku. "No police, he… I mentioned them and he… he panicked. He's… there's something wrong with him, his skin's turned black and he's scared of everything…"

The woman went to say something, but Natsuki missed it when something exploded in the distance. Her eyes went wide, but before she could say anything Izuku stood up and ran on all fours again, this time hurtling away from her and toward the explosion. Natsuki pocketed her phone and took chase, using her explosions to speed herself up.

"Izuku!" she called, before sliding to a halt when she saw the wreckage that was the street outside the alleyway, the roadside strewn with rubble from a blasted-out section of bank. Several unsavoury-looking individuals were running out of the hole, one of them breathing smoke of some kind. Every one of them was wearing a mask; clearly they were at least somewhat organized.

Izuku was running directly for them, on his feet now, sprinting low to the ground. One of them, a larger man likely with some sort of strength-enhancement Quirk, turned to face him. Natsuki saw his eyes go wide and heard a shout of warning die on his lips as Izuku slammed into him with a shoulder-tackle. The man went down hard, Izuku rolling over him to lunge at the man with the smoking mouth. He and the third man, actually a woman judging by her build and the long braid hanging from the back of her mask, both turned to face Izuku.

Izuku slammed a fist into the smoke-guy's face, knocking him backwards, before the woman's fingernails grew at least six inches in length, wickedly sharp edges glinting in the smoke-hazed sunlight. She lunged right back at Izuku and slashed at him with those nail-knife-things, giving him a wicked cut across the chest. Natsuki, circling around to try and help Izuku, saw a long wound open up in Izuku's torso, and winced.

Then Izuku snarled like an angry dog and grabbed the woman's face, throwing her to the floor and stomping on her stomach. He snarled again, raising a fist he could probably kill the woman with, and Natsuki charged in, grabbing at Izuku's arm and screaming his name. Izuku nearly threw her, before freezing.

"N-Naachan…?" he said that stupid kiddie nickname like it was the first time, looking over at her with wide eyes. ""S-sorry…"

A massive figure came through the hole in the bank's side, arms rippling with muscle. He looked all around, a square jaw jutting from a square face and narrow eyes under a metal forehead protector striped in black and yellow. Death Arms, Natsuki placed him purely based on the fact that his biceps were probably twice the size of her head. Izuku saw him and snarled again, but didn't charge. Instead, he shifted so Natsuki was behind him a little more, shielding her with his powerful new body.

Death Arms took in the demolished villains, and then the sight of Izuku. The latter made him pause, slowly raising his fists, before Natsuki grabbed Izuku again and pulled him back.

"Izuku, stop, he's a hero!" she declared, trying to keep the mutated boy calm. "It's okay, he won't hurt us!"

"N-n-no hurting Naachan…" Izuku said, voice lower now, a growl targeted at Death Arms, who was himself staring at the two of them with his head cocked slightly to the side. "Hurting N-Nine, n-n-not Naachan…"

"Is he okay, kid?" Death Arms asked, staring down Izuku with narrowed eyes. "His Quirk out of control or something?"

Natsuki shook her head, and then froze before looking at Izuku again. Was his Quirk out of control? Had Izuku triggered a dormant Quirk or something while he was gone? What… what was this whole thing anyways?

"No, no he's just… he's…" She looked him up and down again. "Different… this is Izuku Midoriya! He went missing a few years ago, but he's… he's back and he's changed…"

Natsuki's usually calm, collected demeanour was slipping in the face of all these revelations. Izuku was back. Izuku had a Quirk of some kind. Izuku had just smoked three villains and nearly killed one. Izuku was ready to fight a hero just to protect her. Izuku was…

Izuku was panting hard. Really hard. Izuku's legs were shaking and his eyes were half-lidded.

Natsuki caught him as he fell, wincing at his weight.

Izuku was different.

AN:

What is this? I dunno. Probably a bad idea, but when has that ever stopped me from writing before? This is Instinct, a story featuring a Noumu-Izuku and a female-Katsuki because the former has a lot to offer as a premise and the latter is just sort of a thing I like. Is it gonna be Noumu-Izuku/Fem-Bakugou? Maybe. Probably. But who knows? I actually don't yet. But let your characters surprise you and all that.

Izuku isn't gonna be overpowered here, I can say that much. He's got a weird Quirk mix that should prove interesting if I play my cards right, but beyond that his famed super-brain is gonna be a little... off, in this particular story. As you may have noticed, this story is called Instinct, and for good reason.

So... beyond that, tell me what you thought! I'm an absolute review-hound, even if it's as short as 'I thought it was stupid and you're dumb for writing it', though preferably criticism will be a little more constructive than that.

Hope you liked it either way you roll, and I'll be back later with another chapter. See ya!