Dude, I'm in your boat. We have a number of people like that here, they're fine when they're on their own but when they're all together it's a nightmare. There's one in particular who picks and chooses who she wants to associate with and obviously excludes others (myself included). Most shifts I have with her end in tears and I've basically lost all patience. And when I call her out I'm the one who gets in trouble. She can get away with murder all because she's good friends with a supervisor.