Now, you can’t just come in here and tell us she’s a friend of your friends, and not give us any stories
As I said, I didn't ever meet her. I wouldn't call the others my friends (not exactly), but they did have direct contact with her. She wasn't a major topic of conversation, but I did ask what she was like, because I was vaguely fascinated by her. (Even then, I had my own theories.) The gist is that she was/is a manipulative, entitled nutter. Unstable. Mad. Deeply unpleasant unless she wanted something. No one had a good word to say about her. In other words, precisely what we've all surmised for ourselves.
I also think there's another thing here. I can't substantiate this, but I think it may well be true. Someone on another thread asked what her partners found attractive about her. I think I can sum up the process. I've known people like this and I can suss them out pretty easily.
Initially very flirtatious, rapidly turning hotly (and adventurously) sexual. Love-bombing, which is hard to resist. 'Never felt like this before' etc. It's ALL about the Other Party. Life is bliss, for just long enough to have the Other Party fall in love, hard. Cohabitation happens far too quickly, followed by plans for 'Together Forever'. Then there's a slight vulnerability (probably one of her physical issues), making her a little unwell. The Other Party lavishes her with love and care. She bounces back. Then a small meltdown, probably about internet bullying ('It's not fair, you KNOW I only try to help people'). The Other Party leaps to her defence. This pattern continues, slowly at first, then the physical and mental meltdowns pile on thick and fast. The Other Party finds their friends unwilling to hang out with them as a couple and they start making excuses for her, eventually changing their lives to accommodate hers. In time they realise that she is an attention vortex and there is nothing whatsoever in it for them.
She's quite simply a vampire, draining the energy and life out of everyone she encounters. Even us.