I'm really not sure why we do these things you have described. As I mentioned earlier, bpds don't really have their own true personality, I mean, maybe we do but its like total amnesia to know what are personality traits are. To put it simpler, what interests I have personally had in life, I never really knew why I was interested in them to begin with therefore I never really had a true interest to begin with. It was like a foreign concept that I could never explain to myself. I don't know if all bpds go through this across the board or if its hit and miss with people. I personally have no recollection of anything resembling my own personality without it involving someone else's personality traits. I have been this way ever since I was a very small child maybe 4-5 yo. The only thing I do remember from that time in my life, I was always "different". I always wanted to die even at that young of an age to present day. That's not a personality trait though.