I have a friend whos straight up weird

I love this guy he's kind and funny at times but hes socially very strange. He's quiet and on a different wavelength to most people 90% of the time. He's likely autistic he was not an outcast at school but very unassuming and a lot of people thought he was weird but he was never bullied.

Him and his brother who is also my friend and is normal don't get along very well a lot of the time but they can't get away from each other as they're twins who share the same friend group. They often have verbal fights and are very short with each other. Occasionally the dude who's not that normal will get violent with the normal one out of frustration but its usually due to aggravation from his brother it's never out of nowhere even if it is an extreme over the top reaction. He should have grown out of that by this stage, but it happened again while his dad and the twins were in the back seat of a car the dad and his brother were poking him on the leg which annoyed him and he started elbowing his brother next to him hard, clearly very angry and this annoyed the brother because in his eyes it was a huge overreaction he then poked his leg again as retaliation because he claims he didnt want to resort to violence but didnt want to let his brother think he could get away with that kind of behaviour. He then elbowed him again at which point their dad put him in a headlock.. I don't know the rest and I've only heard one side of the story and I dont want to bring it up anymore but to me theres some serious problems going on for one of the brothers and his family.