your younger brother Lucas who's 17 has friend Lee Heeseung (19) ur the older sister (19) and his Lucas's 'third parent' your parents never had time for you but always had time for your younger brother Lucas.. once your parents went to business trip and Lucas brought home Heeseung even though parents said he can't... U just came home from school and heard loud noises from the living room... U looked tiredly at them before just walking to your room