My brother keeps trying to fight me and I dont know what to do.

My brother is 17 yrs old and im 14 we live in the same roof with our parents. and he keeps trying to fight me whenever our parents is not home and sometimes I tried fighting back but it just make things worse and yesterday we fought and he punched me in the face,neck,back,and shoulders and when he punched me in my eye which my eye starts getting red and my body is just covered with bruises but sometimes I just ignore him but I just couldnt take it anymore and fought back and I dont know what to do im afraid to tell my parents what happened cause I dont want them to fight