Why nobody gets this, I'll never understand. We are multi-faceted organisms with light aspects and dark. We respond or react to others, based on how they behave and interact with us. Each person we spend time with, encourages different facets is us to surface (or come out and play, as I'm fond of saying).
I for one, can be terrifically benevolent, or treacherously bitchy. My dark side is alive and well. I never try to stifle it, because if I did, I'd be half a person, rather than a whole one. Just the thought, feels way too limiting.
It's utterly shocking to me, how most people grow up trying to be one-dimensional. It's inauthentic, it's dangerous to our health, and it's murder on our relationships, because we're perceived as predictable, flat and boring, like a cardboard cutout of a person's image.
Who could possibly sta intrigued with, attracted to, and in love with a life-sized cardboard figure? People who date Borderlines by and large, are one dimensional beings. They're drawn to partners with BPD traits, because their lover's moods and mannerisms are quite liquid. In short, the Borderline holds and expresses all the varied emotions and facets their predictable cardboard cutout has discarded from their own personality since early childhood.
This is not to say that if you become more like your Borderline, you can hang onto them~ but if you learn HOW to reclaim and reincorporate the parts of yourself that you suppressed and killed off as a little child in order to survive in your family home, you'll have a far more richly enjoyable time in life, just hanging out with YOU.