You had an older brother, and he was really protective of you.

His name was Milo.

You'd just come back from school, and Katsuki was with you. You two were assigned a life orientation project. You had to think of some ways that hero's could protect people in safer but more effective ways, there examples of situations, etc.

You and Katsuki were heading up to your room, when Milo stopped you. He said he's gonna stay in your room while this project occurs, because he doesn't trust Katsuki. You rolled your eyes and sighed.

You three were in your room, Milo was on your bed, you and Katsuki were at your desk, working, thinking of solutions to the examples you were given.