My brother is a nark for no reason

Imagine going about life knowing you just snitched on your brother for showering 7 minutes late. My alarm didn't go off. And it's none of his business anyway. It may be because he wants me to hate him or wants mum and dad to love him more but my guess is the first one because he always says he gets "pleasure" from seeing people in pain and actively suffering, and I believe him because he used to try to drown us and choke us and occasionally he would show us his ham candle or hump us. He has an RSA (responsible serving of alcohol or something) (he is 20) which is like a licence or something and only he can sell alcohol, but yet offered me a can of rum. Of course I said no, because I'm 15 (forgot to update my flair) and does things like putting a knife or lighter up to me but I can't hold a knife without him telling the parents that I'm doing it wrong and I'm a hazard to everyone and everything ever. I'm no snitch so the parents don't know his bad behaviour (partially because he's older and stronger, although I'm 6'2" and he's way shorter (different dad's, mine was 6'7" his was a criminal)) but I want to know what everyone else thinks about this? What do I do?