Read the DSM description. If you are a technologist you will recognize the format, it is a set of tests that you can likely apply yourself. While I recommend leaving it to a professional, your own curiosity can lead to quite a bit of learning.
What is treatment for BPD, if you don't mind me asking?
I confess to a personal interest as I've sought at times for things like anxiety and depression, and frustratingly enough would not be able to tell you what treatment I was actually receiving under the name of therapy.
The gold standard is DBT for BPD, and treating other co-occuring conditions. It's hard to find somewhere that does by-the-book DBT, and other approaches can also help, but I might recommend starting with an academic center if possible.
Many times people with BPD see it as a problem with the people around them, and have a hard time connecting the dots that their behavior is the common thread. Not seeing it as their problem, they often avoid treatment, but certainly not always. Particularly as time goes on, many are hopeful for some relief.
I just broke off contact with someone I suspect having BPD after the second time they did a complete 180 from the friendly 2 hrs we had before to zooming into a angry, paranoid state over something trivial that was frightening for me.
Our interactions were mostly them telling me all about themselves, troubles, and what I considered a bit too wrapped up in their family and essentially anything I said was forgotten. But they were nice to have a glass or two of wine with.
After the incident, I said maybe they should seek professional help. They said that they hated that I turned out to be one of "those people" that, when they were being 'different' or 'standing up' for themselves, were always saying that maybe they should talk to a therapist or that something was wrong with them and that they were "disappointed" in me. Over the three days following they tried to shrug it off, bring me gifts, etc. but I figured it best just to go "no contact" as they say online.
Anyway, I don't know if they have BPD (though a friend with a bipolar mom confirmed some things) but it's tough when 80% of the time the person is nice and functional but there are hidden faultlines that rapidly turn frightening.
If I could afford to, I would go see a therapist just to get a different perspective on my life from my friends but it's sad that someone who seems to really need it are in refusal. I recall when my mother told me about her taking depression meds and was sad that she was struggling with that and I had not recognized it but also happy that she had sought help.
How do you detect BPD when the subject is so uncooperative and knows how to act normal enough to trick you?
I suspect someone of having BPD who doesn't want any help at all (suprise?). What will convince a psychiatrist or counselor?