What About the Teen Who Gets Into Trouble With Peers?
First of all, does your teen know that he has FASD? That would be extremely helpful to him- I know that understanding FASD has helped my daughter accept her disabilities and ask for help.
Next, have you thought of homeschooling him? That way you can carefully control the peer group. There's no way that a 15 year old should have girlfriends, let alone a 15 year old with FASD. You could have more control over that if he were at home. There are many good homeschooling options out there.
Suzy Lucier in Phoenix has a method she uses with her FASD teens. I can't remember what she calls it, but I call it "apron strings." When the kid messes up, they're on apron strings. That means they have to be with me 24/7, not more than a couple of feet away (not literally tied). Even if you're in the bathroom, they have to be just outside the door. They sleep on a pallet next to your bed. Believe me, it's HARD on the parent, but it works. After a week or so of this, they get more controllable and you can give them a little more room. Our kids are real mimics and that makes this work, even if they're belligerent. I would say that social outings are completely out of the question, unless you or his dad can be there with him.
If you can keep him out of jail and out of mental institutions until he's 30, he'll probably be ok in life. Our kids grow up late.