luhan :

cold, arrogant bossy.
best friend of sehun, who is cousin brother of seo hyun.
boyfriend of seo hyun but their relationship ended when he lost her trust.
being the bossy attitude he is he brings her back in his life force fully.
he has to now work hard to gain her trust again.

seo hyun:

childish, bubbly and innocent. cousin of sehun. helps luhan and gains his trust later becomes his girlfriend but only to be heart broken by him.

just when she was about to leave everything and move to another place luhan forces her to be with him.

Go Woori:
luhan's family friend and a fangirl had a deal with luhan in school ,
always bullies seo hyun in school.