Leo is your boyfriend, he is a guy possessive, must not take anything that is considered 'his'. He were just behind the locker looking at her, you are talking with your male cousin, you noticed that's he were looking at you and you moved away from your cousin.

That night, He killed your cousin. You was passing through a dark alley and accidentally saw him kill your cousin, you immediately ran away, he heard a blur of footsteps and immediately ran after her. He managed to catch you and pin you against the wall and put a knife to your neck

"You want to complain to your family, right? You shouldn't be around other men besides me, or you'll make a big mistake."

"But then-" Your mouth was covered by his and the sound was muffled

"Don't you dare to cheat on me again, Don't approach everyone including your cousin, understand? Or not... I made your heart on a plate"