The short version of what we are wading through. For the last 6-7 months son has been involved with a woman who has massive mental health issues. It appears that he has put himself in a role of fixing her, getting her off drugs, cigarettes, drinking, harming herself, and so forth. As you may suspect, it isn't going very well. She didn't get off to a good start with me since my first introduction was after he had to have narcan resuscitation after a neighbor spiked stuff trying to kill her boyfriend. Nice crowd. His friends alerted me to that incident since I wouldn't have known otherwise and they felt I should know. For the last few months she basically has never spoken to any of us. Kept my son away from mother's day dinner because she wouldn't come due to us 'not liking her', not that we ever have had any contact with her. The maybe 3 times she has accompanied him to family events she doesn't talk to us. A few days ago he came home to find her cutting herself and had a big fight. She went outside and smoked a cigarette which caused him to go outside and continue the screaming and yelling outside. A neighbor called the police since this was like 3AM. During the altercation he slapped her, so police Baker Acted her and took her to the hospital and arrested him. They let him go the next morning without bond or anything. Reading all the reports I saw he had a restraining order saying to stay away from her and the neighbor pending his hearing on the 15th. Since he was responding to my messages on any other subject, except his arrest, I decided to go to his apartment and see the status. Found her there and the place is an absolute pig sty. He isn't clean and basically just shrugged off the incident as his neighbor being a jerk and it would be dismissed.
tl;dr - He is 27 and there is nothing I can do to fix him, but it hurts like hell to see someone so brilliant be so incapable of good decisions.