Your friend is an alcoholic.
An ex-convict and alcoholic, to be exact. Two years ago, he was arrested for multiple DUIs and an incident at a bar that ended in a black eye and bloody nose (and you should have seen the other guy.) Today, he’s living in a halfway house, trying to kick his addiction and take back his life.
Your friend is a drug addict.
He’s been living on the streets for years, buying and selling and getting high and crashing low. He comes to you every once in a while, and you clean him up, let him stay in your house, encourage him to get better. He never does–but you hope that someday, someday he might be receptive.