Ok, this needs a little bit of explanation.
There's this guy I hang out with. We've been good friends for more than half our lives, since the beginning of secondary school. He's always been VERY peculliar. I kind of admired him for the most part, just doing what he felt without caring what people thought. However, in the last few months, things have taken a bit of a turn.
At Christmas, he went out with another friend of ours who got really drunk, and they couldn't get a taxi, so he left the drunk friend in the middle of Ashton, drunk and unconscious, and went home himself. Anybody who knows Manchester at all probably knows that Ashton isn't the most pleasant place. It was a total dick move, and when we heard about it we made it very clear to him that we didn't think much of it.
Fast forward to a few weeks ago. We went out to a house party with another friend of ours, who also got really drunk. We went to get a taxi, but none of the drivers would let us get drunk friend in, so I said we should find somewhere we could go to get out of the cold and hang around until drunk friend sobered up a bit. We ended up practically carrying him to the train station and hanging out there for a few hours. During this time, dick friend tried to steal drunk friend's wallet, kept whining about how we should just leave drunk friend in the station on his own and go out drinking with the money in his wallet, and at one point, kicked the poor unconscious guy hard enough for him to roll over and belt his head on the floor. By the end of the night, his behaviour was so out of line that I ended up getting a little bit hands on with him and sort of hurt him. We haven't really spoken since that night.
Now, last night, another friend of mine phones me and tells me that he's had to tell dick friend to back off sending really graphic messages of a sexual nature to his girlfriend. The guy hardly knows her and she's getting really creeped out by the whole thing. Anyway, the girl's boyfriend sends him a message telling him to back off, all he gets is a message back saying 'lol'.
Put simply, the guy is on thin fucking ice with a lot of the people we know, and it honestly does not seem as if he even realises that this is not how you behave around people. He really is a really sound guy, but sometimes he acts as if he has no moral compass whatsoever.
The real question I'm asking is, are there, like, mental conditions that could cause an otherwise decent guy to behave this way? Or does it sound to you like he really just is a jerk?