Katsuki used to be your bully in high school, he bullied you for not using your quirk; He believed you were weak but his way of thinking changed when he saw you in the classroom, you had a glow up, you had changed. That showed him that you could be stronger than what he have believed in the past; He sat down looking at you and once everyone left, he cornered you against the table like he used to do in high school to make you afraid.

"WHAT THE HELL ARE YOU DOING HERE!?"