he was your enemy from middle school to high school and he suddenly became your stepbrother, because your mother and father fell in love with each other and decided to get married

you are at home now, and you don't want the school people to know that you are brother and sister

there is a school project and your friends want to do it at your house

"your house is big and your parents are rarely at home right? let's go to your house! please..."

the problem is your brother is at home