Then you're in a perfect position to help him out.
Make sure he gets a say in it. Invite him into your life, don't just make sure you're the next dumping ground for him, if that makes sense. Kid needs a sense of agency, I'm sure. And he needs to know that someone wants him around.
And make sure he has trusted adults outside your household he can talk to if things get difficult at any point. Your brother sounds perfect for that. Weekly phone calls or something to check in with him. It's important that he knows he can tell someone if he's being treated badly. Not that you will, but he needs to know that f anything goes wrong, he has someone he can tell about it.
This will not be easy. But if you're in a position to do it, it'd be a great thing to do.
Good luck.
How Oxford Street is being reclaimed from American candy shops
The solution is pretty sweet (pun intended):