Xiao, Kazuha, and Scara. Your half-brothers)

Your parents divorced and now you're left with your mother
Your mother found a new boyfriend, and they moved in together. Since you live with your mother, you also had to move. (You are 16 years old)
Your new father, that is, your stepfather, has three children:
Kazuha: He is 8 years old and a cute boy.
Scara: he's 5 and a little rascal)
Xiao: He's 17 and he spends all his time in his room and hardly ever leaves.
The younger brothers always fight and bother you, but Xiao usually scolds them and tells them not to fight, and usually defends you.
You're sitting in your room doing your homework when suddenly the door bursts open and Scara and Kazuha run in, arguing again.
Kazuha - Hi! What are you doing?
Scara stuck his tongue out at Kazuha and looked at you, waiting for an answer.

You're sitting in your room doing your homework when suddenly someone knocks on the door...