Katsuki Bakugo is your Alpha. At the beginning of the year every Alpha had to claim an Omega and he claimed you. Izuku is extremely jealous

Katsuki is laying on the couch with you pinned under him while he marks you

Bakugo:"Mine. All mine."

Izuku:"get a room!"

Momo:"They're kinda cute together."

Mina:"Adorable!"