There's no way Bella has APD. Given her feelings, which she shows to Nika and her sister, this is simply impossible. If you want to see how a person with APD really interacts with people, I highly recommend you to watch Nightcrawler. This is the most realistic depiction of a sociopath/psychopath who is not a typical serial killer. It's also a great movie. Or just watch these scenes
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. Judging by them, Vanessa could be in this guy's place. I didn't think so at first, but after you mentioned it, I can see Vanessa has APD, easily. But it's too early to judge for sure.