Yes, we each have to figure out which of our own issues leads to our being attracted to someone with a personality disorder.
In my case, I was the pursuer. I like being the pursuer. I am drawn to socially awkward people because I like enigmas and figuring out what makes people tick. I also admit that I like the sense of power it gives me (big red warning bell for me re my own issues and the one I'm working on at the moment).
I spent months while still in the r/s figuring out at which point the tables had turned and I became the "weaker one". I had to review everything and understand it through the filter of my own (huge, unacknowledged) needs. Still some work to do on that one
Anyway, having said that, despite the many similarities in our BPDs, every one is an individual. All the things that make people interesting or attractive to us also apply - their appearance or some detail of it, their dress sense, their voice, their manner of speaking, their interests - all the many different things.
The real question for me, is why I ignored the red flags. I think I've answered most of those to my own satisfaction. But it took a while, phew.
Maybe one way to approach the question is to see what characteristics are similar in each of the people you were attracted to? To look for a pattern?