Chapter Text
Izuku had promised to take this borrowed power, to make it his own and to beat Bakugo properly. That was seeming harder than it would normally, given the difficulty he was having trouble getting home with one arm in a cast and the other solidly burnt and bruised.
Maybe the general exhaustion wasn't helpful, either, but just trying to get home, navigating doorways and stairwells with thrown off balance, all of it was harder. All because of Kacchan, all because of the stress that getting into UA had caused Izuku, all because of the various difficulties he faced in life due to simply being quirkless until a month prior, only using his quirk three times total.
Once he was home, Izuku felt like death. All that time since he started training, and his body was still oddly used to the life of a less than average middle schooler, praying to collapse in bed after being under the weight of the world's best high school. He'd only been a proper student for two days, that was not a fantastic sign of how his next three years would go.
His mum fussed over him immediately, of course, instantly worried about her son who was trying so hard. It was practically going through the motions, though, at this point. Izuku had been concerning her all his life, even more so as he trained to be a hero. So he made his way to his room after some token reassurance, hoping she wouldn't be too worried.
Taking off the tatters of his first ever hero costume was painful, physically and emotionally. He didn't even look in the mirror, both to avoid seeing the burn scarring too much and to avoid the weird feeling he had at seeing his stereotypically heroic body. Izuku never liked seeing how weak he looked before, but now he seemed to be too unused to his own muscles to think of that body as his own, only something borrowed.
Putting on a plain pyjama tee shirt, suitably labelled as such, Izuku really thought about the day behind him. He was still weak, generally, as proven by how easily he was put out of commission. He was no better than when he was a child, probably, at least by comparison to everyone else. Little kids were out there with powerful quirks, and here he was, a teen who broke his bones thrice since getting his.
… Was it comparable to All Might's situation?
All Might deflated every time he got exhausted and hurt, so it was clearly some kind of natural state he retreated to. Was that his first form? And if so, it meant he was more powerful and capable at controlling his power and stress when inflated. It had to be some other part of One For All, then. Something to help improve in times where being a hero was necessary…
A little more training, especially in a way that would make his physical condition improve, wouldn't hurt Izuku too much, right? It wasn't like he actually knew how to do it, either. Maybe if he just imagined himself ballooning into this perfect, idealised hero, or stretching out into something greater, even if only temporary, like an elastic band.
Smoke started to come off of Izuku a little as he imagined the elastic band. That had to mean something, right? He pictured it getting stretched more and more, just as he pictured an egg in a microwave, and the smoke increased despite his body refusing to become better. Every remaining functional muscle tensed, and he thought about everything that would be better if he could just stretch himself a little more.
And nothing happened. And so the imaginary elastic band snapped back.
POOF!
"… Did I do it?" Izuku spoke aloud. A far younger voice came out of his mouth.
The mirror couldn't have been showing him why, but it was the only thing that might have been. There, smoke dissipating around her, was a small girl no older than a first grader. At least, Izuku thought it was a girl initially, given how his shirt draped so much on her that its printed writing changed to 'Dress'.
Izuku had turned into a child. A child with not a scar on his body. The cast had fallen beside him, and his arm was freely moving, but… That wasn't the upside it seemed when Izuku was hoping to get bigger. He wasn't supposed to be small, he was a hero! He had a quirk now as a teen! He wasn't meant to be young and likely quirkless again! By frustrated instinct, he stomped his foot in despair-
And cracked the floor with ease.
"Izuku?" Called his mother from outside, "Is everything okay?"
"U-uh huh!" Although he was fast to try and keep his mum in the dark about everything involving All Might, Izuku quickly covered his mouth when he heard just how different his voice was like this. There was no way it wouldn't be picked up on by his own mother…
"… Really? You sound-"
Inko Midoriya lived in a world where eighty percent of the population, her included, had superpowers. She was used to seeing some weird things, just not really in her own home. So, to have caught sight of a plain, androgynous green haired child in her teenage son's room was not as much of a shock as it could have been. The kid becoming stressed enough that they suddenly poofed back into the shape of Izuku was the shocking part.
"… I didn't know I could do this." He tried so hard to sound calm and collected, but the concerned look on his mother's face resulted in Izuku again snapping like an elastic band, back to the childish form.
☆☆☆☆☆
Young Midoriya was not the kind of person to message All Might in the evening after school, especially not after having already had a rather big discussion about how careful he had to be with sharing the nature of One For All. It was even stranger that it was a text, not a call, and a message for some quirk related guidance to boot.
All it said was 'QUIRK EMERGENCY, BEACH', meaning the plan was to meet at the usual spot. All Might really wasn't prepared for such a trip, having used up his superpowered form for teaching earlier, but he had contacts with cars. Getting in and out of Nezu's Reliant Robin would be the least of his issues.
Leaving behind the school principal for when this emergency was over, All Might walked as fast as his sickly body could take him to the meet up spot proper. It wasn't really as if he was pushing himself in the same way it took to be a hero, but he still was wheezing a little. Hopefully this wasn't something that would need him at full strength.
Something pulled at the bottom of his shirt. Something small and stubborn.
"Oh, uh, hello, little girl," Being good with strangers was pretty exclusive to be powered up, the deflated form holding far less power, "Where's your parents?"
The big, distraught eyes combined with wild green hair almost made the young girl look like she could actually be Izuku's younger sister or something, especially based on how he looked before the intensive training. Even the baggy shirt draped over her looked identical to one of Izuku's usual go to tees…
"A-All Might…" The kid cried, and only then did the notebook she was holding become familiar, "It's the quirk… It… It…"
… Shit.
"Young Midoriya? Is that you?"
The kid nodded, then clearly put effort into thinking about something, brow creasing. In an instant, there was Izuku, just as teary as ever in stressful situations. "I tried to see how I could improve my skill by trying to power up like you but I just got stressed and suddenly turned small and every time I stress out thinking about it I look like that again but it also was weird because while that young I seem to maintain my strength without hurting myself which implies-"
"Kid, take a breath," All Might wasn't catching all of that, no matter the circumstances, "Start from the start. Why were you pushing yourself after school? Didn't we agree that was recovery time?"
Izuku indeed took a breath, but that only led to the small, teary eyed kid appearing. "The test, and Kacchan, and bad thoughts all yelling at me… It hurt…"
"Yeah, I guess I can't fault you for that," They really were alike, "I'm sorry, kid, I didn't think anything like this would pass down to you. The experts thought I was a unique case when it first happened to me, something that wasn't technically quirk at all. Guess they were wrong."
"This… Isn't part of One For All?" Of course that was Izuku's theory, he was an analytical fan boy at heart.
"Kinda. It's more like… Hmm…" What was a descriptor worthy of such a confusing situation? "A forced vacation. There's a lot of power in that quirk, and a lot of responsibility with it. When I can't be a hero, I feel frail, scary, the opposite of what I should be. That makes this my vacation mode."
"I was feeling small…" Confessed poor Izuku, looking at his little hands, "But I dunno if it's the same, cos I'm too strong like this."
Before All Might could even ask what that meant, he found himself actively lifted into the air by the small child as if he was made of paper. "… Yeah, that's... That's pretty different, alright."
"And it doesn't hurt me!" That part sounded actually exciting to the hero-in-training, "I think cos I'm smaller I pictured my whole body as the egg not exploding but I'm not even really thinking that hard and part of me thinks it might be like that old comic guy with the ants who got really strong when small but that was fictional so I don't really know and-"
"You're rambling on me again," Sighed All Might once he was put back down, "I honestly don't know what to tell you, then. I'm here to support you, but I'm really out of answers unless you want to know how to hide it from people. I guess turning into a little girl would be pretty embarrassing."
"But I don't turn into a girl?" Izuku spoke plainly, and suddenly that was oddly clear. He was a plain looking kid, androgynous, but now that All Might knew that all that changed was age and strength, his perception changed…
Huh. Weird. That would need to be looked into.
"… Never mind, let's just focus on the rest," All Might pinched between his eyes, "We're lucky I came here with Nezu driving, we should get this accommodated for at school as soon as possible."
"Can I still be a hero when I'm like this?" Asked the kid, just as enthusiastic about the idea as the usual teen.
Of course that'd be highly important to young Midoriya, no matter what he was going through. In theory, since All Might never felt too mentally different when deflated, Izuku could still be just as mentally capable, and there were plenty of short heroes. Plus, with the addition of non-damaging super strength, not to mention other potential skills…
"Would you want people to know about your small form?" That'd be the biggest obstacle.
"Um… Not that it's me," Izuku practically shook at the thought, "But I still wanna be a hero!"
"Alright, kid, let's see what Nezu and Recovery Girl think tomorrow," It was going to be tough, but All Might was going to fight for his successor no matter the circumstances, "Just take it easy, don't push yourself in either form.
All Might knew very well that wasn't something Izuku could fully promise, but it wouldn't be that much of a problem immediately if everything went well. If Izuku could just use his time to de-stress a bit better while in his proper grown form, then that would be plenty of time for All Might to pass down the skills he used before he lost them in that fight years ago. The kid just needed to relax.