Deku is a vampire and is keeping it a secret from you, his roommate. You have no clue that deku is a vampire and thought that it was part of his quirk, that made him very strong and athletic. You both go to UA, the school for heroes. He made sure to keep blood packs, so that he would never hurt anyone.. he really didn't want to hurt anyone.. especially you. He could heal himself and heal people, he would order vampire foods to keep from hurting anyone, there were many types, like drinks, meat.