What an interesting thread. I hope you don't mind if I put in my 2 cents.

I can relate to a lot of what all of you are saying. I am not officially dx with BPD but definitely have a lot of features.
I have a lot of problems with relating to people. When I want to impress someone, I can also act like the class clown a little, like I have to make jokes a lot and laugh and try to make them laugh. I also use sex to get people attached to me.
I switch between feeling superior and inferior to others. I sometimes see myself as superior to others, like I think I'm smarter, more worldly, etc., almost grandiose, like I'm destined for greatness, and most everyone else is lowly and stupid. But at other times I suddenly get very down on myself and feel like I'm inferior to everyone around me. Then I feel very ashamed of myself and start to think I'm been merely delusional the whole time.
I think I split myself, sometimes I think I'm all good, and its me against the world, other times I think I'm bad and everyone else is good and I've been wrong the whole time.
I also don't feel like I deserve as much as other people. Its really hard for me to accept things, gifts, attention, compliments, other people's generosity and hospitality, etc. It makes me very uncomfortable and I get paranoid, start wondering about the person's true intentions, and I start to worry about what will be expected from me in return, and that maybe I won't be able to deliver, and the person will be disappointed they ever invested anything in me.
I'm really insecure and jealous in relationships. Its hard for me to believe anybody truly loves me or wants me. Partly because deep down I feel I don't really have anything to offer, not as much as others have.
But if the person does end up convincing me they really care for me, then I lose interest in them. I start to think there must be something wrong with that person that they actually like me. I also worry they will change their mind at any moment. This is true of all relationships, with family, friends, and boyfriends, even work colleagues. I also tend to see people as a conquest, and once I've conquered them, I feel I can do better and move on to someone else. This is probably more Narcissistic or Histrionic than Borderline. When I'm feeling superior I can also be condescending to others, and that damages relationships.
Deep down I know I don't really want intimacy or a healthy relationship. I don't feel I am able to connect with someone on that deep a level. I'm incapable of trust and my fears and insecurities cause me to sabotoge all relationships. My fear of getting hurt is more powerful than my desire for true closeness and intimacy I guess. I've learned to be content alone.