Originally Posted by Mr Pheer

You have to lay down clear rules and consequences.

I let my GF's 19yr son move in "temporarily" to help him get his life in order. First rule was, no drugs (yes I consider weed to be a drug) for two reasons:
1. You cant put your life back together doing that shit.
2. If you have money to buy it, then you have money to be on your own, so get out if you want to do it.

Made it his job to go get a job. Took a few weeks but he got hired at a local hotel and 4 months later was promoted to front desk manager.

I've set down very clear rules on how my household works. Consequences for being disrespectful, not helping around the house, etc etc. That part was easy because I just had to remind him that he is here as a guest, I'm doing him a favor, I make the rules, and at any time he decides he doesnt want to follow the rules he can pack his stuff and walk out the door.

It took a little adjustment period (on both sides) but he is doing much better. I'm going to start charging him rent after the first of the year (I gave him 45 days notice about this) and I plan on just putting the money aside and giving it back to him as soon as he can get his own apartment.

So yeah its much easier to kick the kid out but you'll most likely never have a relationship with the kid again, or you can be tough and try to maintain your patience, set firm rules and do not bend. Your brother may have to kick his kid out for a few days to help him gain a little perspective on life, living under a few rules and doing better for yourself is better than being homeless.