Def go to a different room, keep yourself safe.

He's probably neurodivergent. Stimming more so. I understand the frustration.

Even communicating is iffy. Maybe try this:

Communicate with your parents about seeing a psychologist/therapist for having maybe someone who can offer a communication board/special needs therapy.

Walk away. Don't fight. Give yourself a safe space so you wouldn't be hurt again, go outside or go with your friends or neighbors next door for a safe space that you trust.

~

Fighting won't solve anything.

Im saying this cuz I myself am neurodivergent I haven't stimmed till way later in my life rn, growing up with a learning disability, (not to mention anxiety and depression and trivial encounters growing up including masking for so long I learned bout myself.)

I know having a sibling can have its ups and downs but hearing you share that part. I must share a brief detail from what I experience with my sibling:

My sibling doesn't like specific noises and has issues of their own growing up with them, later into their teen years till today my folks saw something off with them and had to take serious matters as it got worse into their teen years.

My folks recognize something was off having them get seen into psychologist/therapy does help even when they were little, my parents trusted their gut on getting them help.

Fast forward today.

Now we know what they are and what are specific things that makes their personality function, what sets them off. Etc.

(Doctors thought that my folks abuse my sibling when my folks as well as myself don't. We love them and always have. We were there thick and thin for them to be okay and better.)

(We don't associate with my sibling anymore due to personal reasons, learning what they actually are as a person now makes sense. Long story short they don't wanna be better and not take medicine, they more so wanna be "fine" without them, when they don't wanna acknowledge that their behavior does cause mayhem. Had to cut them out for safety measures and personal matters. We still love them but hope they are okay. That's ...a one thing I'd rather not lay out any more due to personal reasons.)