I am a mid-older teen living at home and preparing to go to college in about a year. I generally keep to myself and only interact with my parents on the most essential topics so I may be simply not understanding this point of view but my 12 y/o brother's behavior seems erratic and violent spontaneously. He does have a somewhat closer relationship with my parents than I do and when I have asked them about his behavior they think it is normal but something doesn't seem right.
On the slightest displeasure (recent example: asking for my seat and me refusing) he becomes rapidly disrespectful and abusive to the point of occasionally creating a dent in a door or wall in anger. I feel the best way to describe him as being a huge bully with an uncontrolled temperament when he doesn't get his way. In addition to this, he has recently started just randomly yelling insults or profanities at people just to get attention. He also has been refusing to follow directions and at times I feel like his behavior (especially when surfing the internet) comes across as rebellious.
He has had some anger issues for as long as i can remember but it got worse about a year ago when he finally found a group of friends that he enjoys being around (parents don't particularly care for these new "friends" and they come across to me as being of the wrong crowd) after being pretty much entirely isolated for his entire life. His new friends have taught him a lot of stuff that is not best learned from older teens.
A side note that may be relevant is that he also definitely has some social issues and doesn't know when/what is funny and when it is not.
Is this a concern that I should push to have addressed by a professional or is this just a rebellious 12 year old being 12 and something that we have to put up with for a few more years?
To clarify: His abuse at times has left bruises on me and/or holes in thinner walls.