13yo and still sleep with parent

I have a cousin, he is in junior high now. He is afraid of thunder, when he is home alone he will turn on all the lamp even if it's just 10am, he will run if he see a cockroach, and the worst of all is he sleep with his parent in same bedroom. We have 2 bedroom upstair, one is mine and the other is supposed to be his, but he is afraid sleep alone. Sometimes when his parent go out till late, I have to wait and stay awake in front of TV with my cousin till they back home. Sometimes I make joke on him because he is growing teenager but still sleep with his parent. Thank God that he is nice, kind heart and smart at school atleast he has something to be proud of :D