Phenioxrising,
He tells we need to know nothing about him when asking if he is o.k or if the girl is o.k. He also says over and over that rules are only if he gets arrested and otherwise stay out of his business. He balls up his fists a lot when threatening "consequences" and we ask what those "consequences" will be, then he says you are not going to like them with the veins popping out of his neck!
He kinda sounds like he's just selling you a con here. It sounds like he's bluffing and puffing himself up because he can see the effect it is having on you. He doesn't even have to have an actual consequence in mind because he's already so amused by how on edge he has you all...like stunned mullets.
Pumped blood veins or not, it sounds hokey. He may be serious, and if his father seriously beat women and that was just normal for him, then it may be more then veiled threats, but it might be dangerous to just write him off as well. He might even be on steroids and none of you know about it? That would explain the over active veins in his throat.
He may have a temper but how many people can actually produce a popping vein like that at will? Not many, not without some help. Steroids can make a person very aggressive, very mean and very scary to be around. He sounds like he is like that naturally, but if he were on steroids, it might account for the popping veins, that's all I'm saying. I might be wrong, who knows?
If he lied about the girlfriends mother getting involved in them moving in together, then he is probably lying about a whole bunch of stuff that you have no idea about. Believe me, we were all his age once, and getting away with a double life was practically the job description of any teenager his age...for the next 10 years pretty much.
He has you all under control using your own fear against you. They say we are all mini-tyrants deep down as well as possessing an ever developing desire to be free at the same time, and we all need to learn how to deal with our own inner control freak...but his is so well developed he should be writing books about 'How to be the best control freak possible and really get the most out of your powers of darkness mwaahahahahahaha!'
Personally I would take phoenixrisings advice...about plonking him in front of him, as well as counselling, though I think that might be more for your own health and to learn better skills of how to handle personalities like his, because it's not something most people need to learn about their own kids.
Hell, I'd have a go right now, after what I've read here. Maybe introduce some really scary looking adults you may know...or find some if you don't have any of that description, and if you can find ones who are taller than him, who stand over him in some way and who don't take his shit! This is me half-joking, but half-not sure if I am joking or not...but probably not.