I'm posting as my Mum is at her wits end with my teenage brother. Bit of background: Mum had 4 kids with my dad, eldest now in his 30s. Stepdad has 4, roughly the same ages. They got together and had my little brother, there's a 9 year age gap between him and my youngest sister. So, big family, lots of different issues obviously going on at all times, so it's fair to say my little brother probably didn't get as much attention on him as we did growing up, but definitely got spoilt money and gift-wise.
He didn't really fit in in primary, he was a bit chubby, young for his age, would rather play on the computer that play out, not many friends. It all changed when he hit secondary school. During year 7, he sprouted up, slimmed out, broad shoulders, Justin Bieber hair cut- you wouldn't recognise him as the same boy!
This is where the trouble started. We found out he first had sex at 12 
He looks older for his age, always attracts older girlfriends. He started getting in fights at school, as the older boys didn't like their exes going for him. He started smoking. Couple of older boys caught him by himself, beat him up, took his phone, threatened to stab him if he reported them, so he refused to talk to the police. Started smoking dope. Last summer, he got his 16/17 year old girlfriend pregnant, shes due about his 15th birthday next month. They are no longer together, they can't speak to each other without arguing, so he probably won't have anything to do with the baby (my mum is staying in contact with the family, and will be in touch with them). Her mother got drunk, started on brother, and when he argued back, sent her two late twenties sons round to threaten to break his legs. Before half term, he got in a fight at school, the teacher went to break it up and got in the way of a punch, so he's been excluded and sent to our local 'bad boys' unit. And we found out today he's been taking Mcat.
Where do we start on this? Grounding him means he climbs out of the house, he doesn't respond to taking stuff away, he's been to counsellers with no outcome, he has no respect for our parents- although he will defend Mum if you say anything to her in front of him. Mums rang social servics, who just reffered her to the drugs charity helpline. School referred him to the counsellor, but wouldn't or couldn't do much else. God knows where he's getting his money from to do all this- he did have a evening job over the winter delivering pizzas, but he's left that now.
Any help will be gratefully recieved, and thanks for reading my essay!