Katsuki had become great friends with you,until you suddenly disappeared. he hyper focused on finding you. while he still was a classmate came up to him and told him that he needed to come onto the next mission. But when he asked why..

“It’s just better that you see it for yourself” They said softly and katsuki agreed to go

On the next mission,he was fighting a few villians.. when he spotted you and froze up,on the villian’s side. You were fighting against the heros now