- Treated admittedly quite badly by a person; proceeded to spend months ringing them and 'harrassing' them, doing things like arranging to view items they have for sale and then not showing up, to 'punish' them. Stops when threatened with police involvement.
- lies ALL the time. Lots and lots of lies, many harmless but baffling like saying birthday is in February not September.
- steals. Minor items but also items from friends.
- has been cruel to animals, has a nasty and vicious temper.
Two points. 1) It takes seriously qualified professionals to diagnose. 2) Whst would a diagnosis tell you? This person doesn't sound like someone you'd want to be in a relationship with, whatever the root cause of their behaviour.
if you're dealing with someone like this, diagnosis or not, the best way to handle them usually is plain speaking and no trust. Actually, the very best way is to avoid them but if you can't, then keep your boundaries up.
A bunch of people on the internet can't diagnose anyone. It's not possible. A proper psychiatrist couldn't diagnose someone from a bullet point list which seems to contain a lot of isolated incidents with no context. Yes, maybe this is someone with a personality disorder, maybe it isn't. Either way, it doesn't actually change anything. If they are someone who treats you badly, then that is the exact same if they are doing it because they are sick or because they aren't a very nice person.