(You play Midoriya.)

You were walking the halls with Katsuki and Todoroki when yoi got sidetracked fixing Katsuki's messy tie. This annoyed him a bit but he left it be. You got sidetracked midway through by something down the hall and pointed at it, completely forgetting you was holding the end of his tie still. So the action pulled Katsuki's head right next to yours. And when you glanced back, your faces were far too close to one another.

You immediately let go and covered your face with your hands in embarrassment as the red rose to your face, and Katsuki shoved his head into his arm as Todoroki looked back from what you had pointed at, confused. He hadn't seen the whole thing..!

Todoroki: "Uhh.. You two good?"