Twin AU.

Katsuki is your twin, and he has anger issues, while you don't. You guys look the exact same: identical.

At U.A. High....

Katsuki was with his group of friends. You, on the other hand, were alone.

A soft spot in Katsuki's heart is there; it belongs to you.

You sometimes call Katsuki by his nickname, 'Kacchan', just to tease him and you always get the best out of him.