If I could only take it back

Chapter 1: In which class A realizes just how lonley deku use to be

"Class, I have an announcement to make," Aizawa Shouta, the homeroom teacher of Class 2-A, said early on Friday morning. All eyes fixed on him expectantly, including Bakugou Katsuki's.

Bakugou held a begrudging amount of respect for his teacher, given how many times he had saved their class's asses. He'd gone to bat for Bakugou when he had been kidnapped, sacrificed himself at the USJ, and even lost a leg in the Final Battle at the end of their first year while he tried to keep Shigaraki from getting to Deku. He was a fucking badass of a guy, so the volatile blond figured he deserved to be listened to when he asked.

"On the way to class this morning, a first year management student accidentally activated her quirk on Midoriya," Aizawa explained. Katsuki's eyes instinctively flickered to his left, where a wall of windows sat. He frequently used the windows to check the seat behind him, where Deku always sat. He had noticed he wasn't in class yet, but figured the little nerd must have been running late. Now that it was confirmed that he wasn't, anxiety began to prickle in Katsuki's chest.

"What kind of quirk?" Uraraka asked from the other side of the room, also seeming panicked. "Is it dangerous? Is he okay?!"

"Settle down," Aizawa snapped. "He is physically unharmed, although..." the man trailed off, then sighed. "Oh, well, I might as well just show you. Midoriya, come in here!"

The door to the classroom slowly slid open, and a head of fluffy green curls poked its way into the room. Katsuki noticed immediately what was wrong with Deku when he hesitantly stepped inside, clothed in their middle school uniform and five inches shorter than he had been the day before. Given the gasps that resounded around the room, everyone else had realized what was wrong as well.

"Um... hi?" Deku squeaked, his cheeks flushing from all the attention on him. Aizawa waved his hand to beckon Deku closer to him until the greenet stood at his side.

"Midoriya was hit with a de-aging quirk that regressed his age to thirteen years old," the hero declared. "His memories have left him as well, so he won't know any of you, either. I expect you all to treat him well." He said this with a pointed glare around the room. Bakugou was aware that his jaw was hanging open like a fish, but he couldn't bring himself to close it. Deku was... so much smaller than he had remembered. His cheeks were full of baby fat, and his curls were even more unruly than usual, like he had gotten out of bed and sprinted into class without brushing his hair. All of his hard-earned musculature was gone, leaving him swimming in the middle school uniform that Auntie Inko had bought a few sizes too big so he could "grow into" it.

His wrists and collarbone were jutting out of his skin, as he was almost scarily thin. He looked like a strong gust of wind could knock him over.

"Oh my god !" Ashido squealed, pressing her hands to her cheeks. "He's so cute!"

The class began to chatter all at once, each of them asking questions to both Deku and their teacher. The nerd's giant eyes widened even more, anxiety clear on his face as he began to inch backwards. Katsuki had a sudden flash of a memory; the entirety of their middle school classroom jeering and hurling insults at Izuku when he stood up to give a presentation to the class. They had harassed him until the nerd ran out of the room to cry alone in the bathroom.

"OI!" Katsuki yelled, screeching his chair back. He slammed his hands on his desk for good measure, just to make sure he got everyone's attention. Once everyone was staring at him, Deku included, he sneered at them all. "You're fucking scaring him, extras!"

"K-Kacchan!" Deku stuttered, relaxing slightly at the sight of a familiar face. "We're in the same class?"

Katsuki softened his expression, his heart in his throat. Looking at Deku now, knowing that the nerd hadn't ever looked down on him, but rather looked up to him, he felt nauseous knowing that he had once destroyed the boy over and over again. He never wanted to repeat that behavior. "Yeah, nerd," he said. "We're in the same class."