This chapter show snippets of Aizawa's initial experience going back in time :)

Aizawa had gotten complacent.

Not that he had known that at the time, but taking out three UA students and a little girl with an overpowered quirk on an excursion with only himself as a supervisor wasn't his best idea. He could have sworn that they had kept their entire raid on the Yakuza as under-wraps as possible. Sure the fight had eventually been dragged up onto the street (and sky, holy fuck was he still stunned just thinking about the miracle Midoriya had pulled off that day) above.

But as far as knowledge on Eri went, there was no way that information got out. Unless, of course, the League had been more heavily involved in the Yakuza's plans than they had anticipated, but they had waited a decent amount of time and no moves had been made. So he'd felt safe taking them out, his own arrogance in his abilities apparently enough to override his awareness of the many logical fallacies that all people relied on.

Hindsight was truly a cursed gift.

Especially when he found himself stuck in the past, dreading the day that spawned one of his worst nightmares and biggest regrets.

His eyes snapped open in fear. But he was only greeted with the dullness of his teenage bedroom. Which was absurd, because he had just been out-

Wait.

The mall.

Mirio.

Bakugou.

Midoriya.

Eri.

Aizawa sat up suddenly, almost tumbling out of bed with the momentum he had thrown forward.

Shit! What the hell happened?

He tried to concentrate, but a dull headache made itself known. Shoving his hand against his face, the hero forced himself to push past the familiar throbbing at his temples and think back to the last thing he remembered.

A twisting sensation had taken over his body, yet it hadn't exactly been pain. What happened? A quirk…?

He flinched, dropping his hand into his lap.

His small hand. What the fuck?

Aizawa shook his head. Concentrate.

There had been a surprise attack, some kind of hit ordered on them. Or something of the sort. By whom, Aizawa could only guess. In the moment, Aizawa had been too late to take action and the would-be assassin fired without repercussion. The shot looked like it had been aiming for Problem Child, but it hit Eri instead. And then Eri's quirk, which he had personally been working with her to help her gain control, went crazy. It must have been some variant of trigger, which made the man's blood boil.

How dare they shoot any of the children. If it had been aimed at him, perhaps he wouldn't be this pissed, but the kids had been through too much and didn't deserve such danger. But a part of him—the part that was still very much in denial—knew that they had already been exposed to the hell of the real world and none of this was technically new to them. Midoriya had been attacked by a villain in a mall once before. But that didn't mean that the kid should avoid having a regular life just to flee the unwarranted risk.

Aizawa scrubbed at his face as though attempting to rub away his anger. He had to focus and list what he knew. He had to do damage control.

Eri had been hit with some kind of trigger.

Her quirk went out of control.

And then Aizawa woke up here, in what looked like his teenage bedroom.

With small hands and a lighter body.

Reluctantly, Aizawa tugged the comforter off of his legs and stood up from the bed. He hobbled over to the bathroom, narrowly avoiding an unfortunate accident or several via tripping over his own goddamn feet.

Eri's quirk rewound the time of people in the present, it didn't send people into the past. What kind of nightmarish hellscape was this? This was impossible. There was no way this had happened, Aizawa refused to believe it.

Yet, here he was, in his younger body in an empty apartment that had been sold a long time ago with a few objects that he had long since used or thrown away.

He… wasn't sure what to do with all this new information. Perhaps the future he remembered some strange kind of dream? Maybe it was the product of a quirk. But he had no way to verify that, so that was an irrational train of thought to linger on.

Aizawa would just have to… go on with his day and figure it out while he managed day-to-day tasks.

Like school.

He stared at his phone, lying inconspicuously on his desk. With a strange reluctance, he forced himself to grab it, tapping on the screen. He was met with a picture of a small bundle of stray cats he had found and set as his background picture for at least six years.

He swiped on the screen and quickly realized that whether the hell he woke up remembering was a dream or real, he couldn't remember which of his many iterations of passwords he was using at the moment. It felt as though the locked icon was taunting him. Luckily for him, at the very least, the date was accessible from the lockscreen, so at least he knew the day of the week.

Monday. Of course it was a Monday.

Just his luck.

With a heavy sigh, he decided to go with the flow and figure things out as they happened. Aizawa was just glad that when he opened his closet, he was met with the familiar UA uniform with only one button on the shoulder. So he was already in the hero course. That was good then. He must be in his second year at the moment.

Maybe he could ask Nezu for help?

The man (teen?) paused and thought about what he knew (or at least thought he knew from his "future" memories) about the principal.

Yeah no, that was a bad idea.

He would just go to class and do his best not to cry at the sight of Shirakumo, and move on with his life. It was almost ridiculous, now that he thought about it, that he had such a heavy emotional response to the realization that Shirakumo was still alive. If this was all some quirk or dream, then its consequences were getting a bit absurd.

Perhaps that simply meant that it was all real. After all, Aizawa was one to live by his senses and perceptions above most everything else. If this was his perceived reality, then so be it. Even if it turned out to be false, there were still things he could do with this knowledge and experience.

Assuming the knowledge and experience actually translated into reality. There was always a chance that it was all made up in his head.

He would just have to test it over the next few days.

The next few days went by with little hassle, excluding the moment he laid eyes on Shirakumo and almost burst into tears. Damn teenage hormones.

Aside from that… almost disaster, he had finally managed to unlock his own damned phone and change the password the day after he woke up with the strange memories of the future. That helped him get by and figure out exactly what was going on in the world at this moment. Not to mention, his quiet nature worked in his favor, allowing him to observe everyone around him and gather hints as to how he should act to blend in without arousing suspicion from his peers. It also didn't hurt that he had a reputation for pretending not to care enough to remember important details or previous conversations, even with his two closest friends.

And Kayama. But he didn't count her as a friend until much later.

Or wouldn't have counted?

He hoped that this was all some dream that screwed with his head, but with how much he struggled to remember things that he should by all means already know, he had the sinking feeling that this was real. Besides, he remembered the details of the future much too vividly for it to have been a dream, especially since it had already been several days since he woke up. No, that future was very real. He had to believe it was.

Which meant that in just a few days, Shirakumo would…

No.

He would save Shirakumo if it was the last thing he did. He wouldn't let his own weakness get in the way of his friend's life. Not this time.

After unlocking his phone, he quickly realized that he only had about a week or so until that damned mission where Shirakumo had…

He had under a week to figure out how he was going to save his best friend from a fate that he wasn't even sure was real. Aizawa hated that that day was going to become another test to see if his memory of the future was real or not, but he had no choice in the matter.

He couldn't help but admit to himself how helpful these memories were in the heroics training exercises. It wasn't as if he was magically perfect at everything—his balance was horribly off, and he found himself tripping over his own feet a few times—but he was able to semi-successfully emulate techniques that he most certainly would have failed at before. And honestly, his inability to account for the massive change in proportions and weight distribution was a boon for hiding his sudden increase in practical experience.

Of course, during one of his long musing sessions in which he tried (and failed) to come to a conclusion about his strange new memories (or visions?) of the future, he stopped to consider why he was attempting to hide it at all. Other than the fact that he would get more jeers from the other assholes in class, Aizawa wasn't sure that any attention from teachers would necessarily be a bad thing.

Unless they suspected him of being a villain somehow.

Which was kind of absurd, but perhaps it seemed more plausible with his memories of the future. The paranoia and fear that had overtaken UA was incredibly damaging and had lasting effects. There was no way that teachers in this time period would have any such suspicions.

Maybe they would call him out for foolishly "hiding" his talent, but that was the worst they would do… right?

Or would they be right to be suspicious?

Aizawa only had his (alleged) time as a teacher to reference. There hadn't been such an atmosphere of suspicion until after the League of Villains showed up. But now that he thought about it, he wouldn't have any idea what the staff were doing behind the scenes as he went through his daily school life without a care in the world. Maybe there was some threat he was unaware of by nature of his position as a student.

Or maybe he was being paranoid. But it was always better to be cautious than to let his guard down, right?

After all, if his future memories were, in fact, memories of the future that actually happened, then he was only in this whole mess because of his own carelessness. So he simply wouldn't let himself be that careless again. He would be alert and on guard at all times and ensure that everything went the way it should.

He would save Shirakumo this way, if he had anything to say about it.

Maybe this time they would actually start an agency together: him, Yamada, and Shirakumo.

Perhaps he should have heeded the warnings about changing the past, but Aizawa refused to stand by and do nothing when Shirakumo was at risk and in danger. He would change that one event and deal with the repercussions if he had to.

And if it turned out that he did irreparable damage in the process, so be it.

There was no turning back for him, he had made his choice long ago, if his memories of late nights spent sobbing and cursing at the stars, demanding a second chance to do better, be better, were real.

And if just under a week later the same damned battle gone wrong began to play out before Aizawa's very eyes, he knew that his mind wasn't failing him and the memories of the future were as real as the flashes of pain shooting through his limbs. He would fix this.

Aizawa blinked awake, groaning as the throbbing behind his eyes hit him like a train. He let his eyes slip shut again, if only to get away from the painfully bright fluorescent lights overhead. The strong scent of disinfectant burned the inside of his nose.

Ah, he must be in the hospital.

After his fight with that villain. After…

Had he succeeded? Had he failed? He hadn't even been able to check before he passed out cold. He must have pushed himself too hard for his teenage body, but he couldn't bring himself to regret it.

But if he were recovering in the hospital, knowing his quirk, why had they left the lights on?

He was sure he was in the hero ward of the hospital, given the lack of chatter that was characteristic of the public section of the hospital. Although there was an annoying voice…

Wait, he knew that voice.

Yamada?

He forced his eyes open despite the immediate sting he earned for his troubles.

"Yamada?" he groaned.

"Hey hey hey! He's awake!" Yamada shrieked.

Aizawa let his eyes slide shut again, groaning, "Keep it down, would you?"

"Right! Sorry," he replied sheepishly.

"...did everyone make it out okay?" he couldn't help but ask, hoping that he had actually managed to make a difference.

"Yeah. I heard you were amazing!" Yamada cheered, walking over from the other side of the room, "Shirakumo over here managed to get his foot stuck under the collapsed building, probably because he was so worried about you, you dumbass, so he had to get surgery. But he's right as rain and was awake just a few minutes ago! You just missed him. But we all know how much you love your sleep, so I guess it's not a surprise."

Aizawa's eyes shot open once more, "He's okay?"

He stared at Yamada for a moment before forcing himself to sit up. His muscles protested the movement, practically screaming with agony (damn, he was probably going to be feeling this soreness for weeks). But he had to see it with his own eyes.

And sure enough, in a bed on the opposite side of the room, was Shirakumo. Shirakumo, bandaged and clearly exhausted, but alive and healing.

He was alive.

And that was enough for Aizawa.