She...seems to gravitate to other people with a burden like hers - broken people who've healed themselves, or those who haven't and might find themselves in flux (that she could influence), though I don't think she'd like to term it so much 'broken' as...'people with sharp edges,' like her. Though she doesn't 'gravitate' so much as people sometimes actually want to get to know her...and once she's past her suspicion/paranoia (this takes forever), then that's what she gravitates to: those who see, and accept her. And it's important that they be honest about and with themselves, as well. People with a sharp mind, who still know how to make mischief are top notch, in her book. Especially if they can keep pace in a verbal spar (....or be a good sport when they lose, and not threaten her >_>).
The 'why' of it all is likely that...that's all she knows. She's had a screwed up life, and wasn't really socialized at all, and doesn't believe in altruism as a concept, either. It's hard for her to want to establish relationships, when all she sees is someone who wants to use her for one reason, or another...and some bad shit with people she let in went down last year that only reinforced that mindset. Getting it through her head that you're not that is rough, thanks to her paranoia. So, she ends up preferring to stay at arm's length, interject with snide insights, and occasionally be lured in with philosophical debate. Or more snide commentary from others.