Another time travel plot, yay! This was started in Dec 2018 and I think I continued writing it over the next few months?? Originally it was just going to be Izuku and All Might having a cute reunion in front of Tsukauchi, but then I got invested in the story, and it spiraled out of control, lol. I was also gonna post this in one chunk but then I realised 20k words was a bit too much for one chapter, so I managed to split it up (:

Take care of yourselves, and I hope you enjoy!!!

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Summary:

By a Quirk or twist of fate, Izuku and All Might are sent back in time to when Izuku was seven. Alone together and armed with knowledge of the future, they're not going to let tragic stories unfurl in the same way.

Quirkless or not, Izuku is going to save as many people as he can, and even All for One can't stop him.

CW: Blood & Injury, Canon-Typical Violence, Temporary Character Death

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Chapter Summary:

The adventure begins, Izuku's doing his best, and Naomasa didn't realise his friend had a son...?

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Izuku suddenly jolted in his seat, flinching so violently he loudly jostled his desk and garnered looks from his- his... his classmates. They were only faintly familiar, vague faces regretfully stored in the back of his mind: he couldn't even remember their names. Except- except one of them.

The ash-blond boy with spiky hair was glowering at him with scarlet eyes, lip jutted in an ever-present sneer. His face was rounded with baby fat and there were small explosions popping in his sweaty palms from time to time. Kacchan sat at the desk in front of him, twisted in his seat to scowl at the disturbance while all the other kids tittered tauntingly.

It would've been a perfectly normal day, if it wasn't for the fact that Izuku distinctly remembered fire and pain and fear, and then sudden, blinding whiteness, and he was shoved back in his seat in school, feeling like he'd been startled awake from falling in a dream. He suddenly gasped in a breath, going to raise his hands to tangle them in his hair to ground himself, only to freeze again and see the tiny, skinny fingers and pale, unblemished skin, no scars or disfiguration in sight. There was no warm thrumming in his soul that indicated the presence of his Quirk, One for All, and a look at the uniform he was wearing confirmed that he was probably around seven years old.

"Everything all right, Midoriya?" The teacher asked, annoyance in her tone.

He clenched his hands around the edge of his desk so hard it hurt, because no, nothing was all right, he was supposed to be in his twenties fighting a villain with a powerful fire Quirk, losing against the bad guy despite his power and talent since he was more focused on protecting the many civilians, getting more and more scorched with every blast he desperately intercepted, and then he saw a tall man with a mane of wild, golden hair who was about to be hit and-

And... Izuku hadn't been quick enough. All Might was engulfed by the inferno. The young hero had thrown caution to the wind and leapt over, dispelling the flames with a kick. He'd wrapped his arms around All Might, too focused on him to notice the next attack coming. There was fire and pain and fear, and then blinding whiteness and-

"I'm f-fine," he responded belatedly through tears.

The teacher didn't look convinced, but clearly didn't care enough to push the matter, instead continuing on with maths that was laughably easy. Izuku was thankful for the mind-numbingly simple tasks, allowing his mind to wander as he quickly scribbled down the answers, all the while trying to work out what had happened to him whilst tears dried on his freckled cheeks.

He had died, there was no doubt about that. Was this some kind of after-life? Was he punished with an eternity in his awful school days? But what about All Might? Did he survive? The phantom pains on the boy's back insisted otherwise – those flames were hotter than Shouto's. If All Might was de- gone too, where was he? Had he returned to a random moment in his past, too?

Wait... Past. He was in the past. What if... what if it was the effects of some kind of Quirk? Time-related Quirks were uncommon, and the chances of one powerful enough to send him so far back were almost negligible, but... It was possible.

"Deku, shut the fuck up," Kacchan snapped, slamming a fist down on his desk and scorching the edge of Izuku's worksheet.

The boy didn't even flinch, too used to his friend's outbursts, and since they were on relatively good terms in the future, he couldn't find it in himself to be afraid of his childhood tormentor. He merely blinked slowly at his young classmate, both parts terrified and fascinated by the possibility of being sent back in time. Kacchan slowly withdrew his arm, expression morphing from anger to unease to contempt before he turned back around with a huff.

School couldn't end fast enough. He'd been called upon in multiple classes for muttering and not paying attention, only to humiliate the teachers by giving the correct answer without even raising his head. There was something cathartic about their reactions when they realised their attempt to embarrass the poor, pathetic, Quirkless kid had backfired.

Finally, the final bell rang. Izuku almost ran straight out before remembering his age and knowing that his overprotective mother would likely be picking him up. He decided to lurk on the school grounds, padding across the grass as he contemplated his plan of action. The grass was still a little damp from a recent downpour, and he found himself slipping and stumbling a few times, which gave him the idea of practising his fighting moves.

His body was so small and weak, and every time he threw a punch he was surprised by the minimal force behind it. It took a little while, but he eventually grew accustomed enough to his young self to be able to successfully execute a simple flip, only to skid on the grass and face-plant into the dirt, an unflattering wheeze expelled from his lungs. He rolled over onto his back and stared at the sky for a bit, getting his breath back.

All Might's agency was too far for him to travel alone while he was a kid, which was frustrating, but something he probably needed to get used to. His mother likely wouldn't want to waste money on such a futile trip, and even if he did somehow manage to get there, unless All Might was in the lobby when he entered, no-one would take him seriously. And if All Might didn't even remember him...

Izuku shook his head a little, frowning and picking himself up: thinking like that wasn't helpful.

He also wouldn't be able to get into UA to explain things to Nedzu and try to work something out, and the likelihood of running into Aizawa while the man was on patrol was slim to none. That only left one option...

*

Naomasa was having an odd day, but being friends with All Might tended to have that affect, just not... not usually to this extent.

It was a perfectly ordinary Tuesday, and Naomasa was finalising some reports he didn't quite finish the previous night. His phone rang, and since it was All Might, he deemed it important enough to answer.

"Tsukauchi-kun," the hero sounded a little frantic- completely out of character.

"What do you need, Yagi-san?" Naomasa responded smoothly, even though he'd taken to nervously tapping his pen against the desk.

"I need, ah... would it be possible for you to look up the whereabouts of someone for me?" Yagi asked, growing a little meeker by the end of the question.

He frowned down at his paperwork before leaning back in his seat and pushing himself along to log into his computer. "A criminal?"

"Well... no..." The hero grew unexpectedly quiet before clearing his throat. "A civilian child?"

Naomasa's fingers stilled over the keyboard and he was silent for a moment. "That's... not something I can give away freely, not even to the Number One Hero."

"I know, I know." Frustration spilled into his tone. "I just wanted to see him, after... what happened."

"What happened?" He inquired, worry etching itself on his features.

"Shit," Yagi swore in English, a little faint, as if he was facing away from the phone. "I need to call you back later, Tsukauchi-kun. There's a villain."

"Right," he paused, then added, "Stay safe."

The line went dead and he was left to stare confusedly at the computer monitor. He sighed and rolled back over to his reports, knowing he'd have many more to file by the time All Might was done with his crime-fighting spree.

Afternoon arrived, and he was ready to leave for his coffee break, needing the extra buzz to keep him awake. He grabbed his car keys and stepped into the reception area, glancing around and offering cursory smiles to his coworkers and wholly intending to stride right outside until he was fixed under a bright green gaze. The tiny kid pulled himself away from the front desk, thanking the receptionist and immediately bouncing over to the detective.

"Tsukauchi-san! Thank goodness. It's been a crazy day, I have so much to tell you... Could you please call All Might-san for me? I need to talk to him!" The child beamed brightly, hopping on his toes and causing his mop of green curls to bounce around his head.

"I can't do that for you, kid, sorry," Naomasa apologised gently, feeling like he'd been shot when that innocent grin faltered. "I'm on my break right now, so if you-"

"Could you call Yagi-san instead, then? Please?" The boy stared up at him with wide, round eyes, clenching his hands in the fabric of his All Might hoodie, desperation seeping into his tone.

Naomasa paused, a jolt of apprehension curling in his stomach. Paranoia was common in his line of work, but never before had he been so unsettled by someone so young and harmless.

The kid pursed his lips, raising his small hands in a cautious surrender. "S-sorry, I didn't mean to scare you. I'm his... friend? Yeah, I guess we were friends... He knows me. At least text him and ask him, please?"

He remembered how odd Yagi was acting - asking after a civilian child – and now there was a, presumably, civilian child knowing his real name and seeking him out. It would've been an awfully big coincidence if the two events were unrelated, and since his Quirk hadn't flared up to indicate any lies, it was worth trying. Naomasa stared down for a moment longer before grabbing his phone, obliging the kid's peculiar request.

Naomasa

There's a kid here who knows your name and wants to see you

Yagi

Green hair, green eyes, freckles?

Naomasa

Yes? You know him?

Yagi

omw

The detective raised his eyebrows. His friend rarely used texting slang, usually only when he was in a rush. He slipped his phone back in his pocket and blinked at the child, whose hope seemed to glow in his gaze.

"What's your name?" Naomasa asked, deciding that this conundrum was more important than coffee as he knelt down on the rough carpet.

"Midoriya Izuku!" He responded cheerfully, voice squeaky and soft, nothing but warmth and friendliness in his posture.

The man tilted his head with an amused smile. "You seem to know me already, but I'm Detective Tsukauchi. It's nice to meet you, Midoriya-kun. What did you need to talk to Yagi-san about?"

"A-ah, um..." He shifted on his feet, guiltily avoiding the adult's eyes. "It's a secret... I don't think I can tell you. Sorry."

Naomasa might've been inclined to dig deeper, but the front doors burst open suddenly. He was back on his feet within a second, automatically reaching out towards the child in case there was danger, only to immediately relax as he saw his friend frantically scanning the room. Yagi's blue gaze landed on the boy, and for a moment both of them stared at each other, then Midoriya darted over to him. The man stooped down, his large hands easily cupping the kid's sides and scooping him up into the air, both of them laughing joyously.

"Put me d-down!" Midoriya spluttered out through giggles, squirming in his grasp.

"But you're so small, young Izuku!" Yagi commented with a wide grin, but complied nonetheless, eyes crinkling at the edges.

"I don't want you to strain yours-" The boy cut himself off, blinking suddenly as his gaze trailed over the man's bulky form, noticing the blond hair was curling around his face rather than sticking up. "Oh. Oh! It hasn't... you're..."

Yagi patted his left side happily. "I'm perfectly alright, my boy."

Midoriya's expression was filled with wonder, and fat tears rolled down his freckled cheeks. Naomasa felt his heart break a little at the sight, taking a halting step forwards before realising he might be intruding on what seemed to be a personal moment. Yagi tangled his fingers in the boy's messy green curls, ruffling fondly, before lifting his glowing blue gaze and pausing uncertainly as he noticed the observer.

"This is the kid you wanted to find?" Naomasa muttered with raised eyebrows, lips curving into a smile at the sight of his friend looking so genuinely happy.

"It seems he found me. I should've expected that, really," Yagi chuckled, shaking his head and sighing faintly as he dipped down and picked up the boy again, holding him securely against his chest. "Crybaby," he mumbled affectionately, pressing a hesitant kiss to the kid's head.

"I d-don't understand how this happened," Midoriya breathed, using the sleeve of his hoodie to wipe his eyes, despite more tears already spilling over.

"I don't either, but... I'm glad." Yagi's lips twitched into a frown and he lightly rapped his knuckles against the kid's shoulder. "You're too selfless. You should take better care of yourself, my boy."

"So should you," he retorted with an adorable pout.

Naomasa glanced between them, mentally racking up the similarities and the unexpected closeness that could only be described as familial. "Is he... your kid?"

Both of them suddenly went bright red, stuttering out denials and trying not to look at one another. The detective pursed his lips in an attempt to keep his expression neutral, because his Quirk pinged softly a few times when they denied their father-son relationship – when people believed something enough, it could pass as the truth, which was often a pain in investigations, but currently quite entertaining.

"Right," he said bemusedly, successfully causing the duo to sputter into silence. "Well, I'm on my break. Care to explain what this is about?"

"Yes, I suppose you should know," Yagi responded with a sheepish smile.

Midoriya patted the man's chest to get his attention, expression concerned. "Ah, I need to get back to my mum. She's probably worried about me after I ran off to get here."

"Oh," the hero muttered, a little faintly, adjusting the kid in his grasp and glancing over to the doors. "She's not going to be happy."

"No," the boy agreed nervously.

"The sooner we return you, the better, then, right?" Naomasa prompted.

All three of them exited the precinct, stepping out into murky sunlight and overcast skies. Yagi didn't seem like he wanted to let go of the kid any time soon, keeping him carefully seated on one arm, the other wrapped loosely around his torso like a seatbelt to keep him from falling. Midoriya, to his credit, didn't seem that bothered, merely swivelling around as best he could and pointing the way with a tiny hand dwarfed by the chunky sleeves of his All Might hoodie. The hero seemed enamoured with the boy, occasionally glancing at him with the softest expression Naomasa had ever seen on him; it was usually all hard lines and dark shadows contouring his face, but now his eyes were gleaming with life and his smile wasn't the usual strained one he put on for hero work, instead small and genuine and adoring, like the child was his world.

They walked in mostly silence. Yagi and Midoriya would occasionally lean their faces close together and whisper to each other, usually coming away with secretive smiles that looked all too similar. Naomasa shook his head in disbelief, chuckling faintly. A slim woman with long green hair was standing in front of a bench, clutching at her purse with her jade gaze flitting around frantically, tears trailing endlessly down her pale cheeks. She glanced over at the sound of footsteps and visibly relaxed, rushing over and holding out her arms, holding Midoriya tightly even though he was a little too big for her to carry.

"Don't do that again," she muttered wetly, fingers digging a little into the boy's back as she hugged him closely. "You worried me."

"Sorry, mum," he apologised in a gentle, soothing tone, leaning out of her grasp enough to wipe away her tears and offer a smile. "I just needed to find Detective Tsukauchi-san to contact- uh..."

Yagi shrugged at the questioning look, brushing a hand back through his unruly golden hair and offering a nervous sort of smile. "Yagi Toshinori, but you... you probably know me better as All Might."

Now Naomasa was even more confused. It was obvious that the father-son pair were incredibly close, but why was he introducing himself to the boy's mother – surely, they knew one another already? If they didn't know one another, why was his friend so calm about revealing the closely-guarded secret of his civilian identity?

The woman's cheeks bloomed a delicate pink as she skimmed her gaze over the muscular man, clearly working out that he was telling the truth, despite the casual clothing and different hairstyle, and the last of her protectiveness flooded from her posture. She set down Midoriya with a heavy huff, but kept their hands firmly linked at their sides.

"I-it's, um, it's nice to meet you, All Might-san. I'm Midoriya Inko." She tugged self-consciously at the hem of her blouse, but there was a certain steely strength to her that the detective couldn't help but respect. "T-thank you for looking after my son, and, um, sorry if he bothered you, y-you probably have people to save-"

"It's no problem, Midoriya-san!" He assured with a blinding grin and a thumbs-up, puffing out his chest a little and resembling his hero persona even more. "Looking out for lost children is just as heroic as defeating villains."

"I wasn't lost!" Midoriya exclaimed indignantly, trying to look irritated but having to hide his smile behind a sleeve.

"Of course not, my boy. But I still need to look after you." The man knelt down, making a little noise of surprise when the kid immediately leaned forwards and embraced him, causing him to chuckle and wrap his own arms around the child. "You're a lot more vulnerable now."

"I only just got used to protecting you," the boy mumbled into a shoulder, both of them snickering softly – Naomasa didn't even know what to think of that cryptic statement.

Yagi suddenly tensed up, leaning out of the hug with his hands on the boy's shoulders, staring at him with wide eyes. "Tomura."

Midoriya blinked before a shocked realisation flickered across his features. "Tomura. We can..."

"We can!" The hero let out a burst of overjoyed laughter, smooth and uplifting, and in his excitement he scooped up the boy again – Naomasa's heart warmed, but the detective side of him was already trying to work out what the hell was going on between the two of them.

"Oh, um..." Midoriya caught his mother's tearful gaze. "Mum, would it, uh... w-would it be okay if All Might and Tsukauchi-san came over later? There's something important I – we – have to explain... Wait, are you free, Tsukauchi-san?"

"Yeah, I should be," Naomasa responded with a perplexed blink, glad that his suspicions had been confirmed and something was definitely odd about the duo.

"Goodness - All Might? At our house? Um, I... Izuku... I'm sure he has lots of important things to do..." The woman fumbled, cheeks aflame once more, gazing up at her son in the man's careful grasp.

"Not more important than young Izuku," Yagi denied without hesitation, only to clear his throat awkwardly under the astounded gazes he got in response. "W-what I mean is, um-"

"They're both going to be there," Midoriya finished with a faint snort of amusement.

His mother looked over at Naomasa, her expression somewhat disbelieving, and he stared back at her with a similarly bewildered countenance. She seemed smart enough to finally notice how peculiar it was that the two of them seemed like they'd known each other for a lifetime already, twisting a lock of hair in her fingers and nodding slowly, uncertainly. Midoriya beamed and rummaged in the front pocket of his hoodie, withdrawing a phone with the same theme. Yagi took it with a chuckle, making sure the boy was secure on one arm and using the other to navigate the device, struggling a little to use the tiny keyboard and input his number.

"R-right. Okay. I- I guess Izuku will... text you?" She asked distantly, looking and sounding a little like she was about to pass out from shock.

"Sounds like a plan," Yagi agreed, passing back the phone before delicately placing the child back down. "See you later, my boy!"