Joffrey was clearly an idiot, not a genius.
Also, I haven't seen any evidence yet that Vanessa is psychotic. She has freakishly high IQ, but this doesn't mean automatically that she's a psycho. She could be, but I doubt it.
I had an impression that she likes to play with people who aren't very nice. She is playing some game with the Holgersson asshole(s), but she hasn't finished that game yet. And she has a plan. Possibly a better one than cylons had...
When she met Bella in the cafe last time, she figured out almost instantly that Bella also has some kind of a plan and is trying to use her to play a game of her own. She tried to find out what her game is and why is Bella trying to use her while playing a dumb airhead herself.
She also probably isn't very sure how nice of a person Bella really is, since people know more about the queen bee Bella who can be quite cruel sometimes.
And she likely thinks that Nika has also something to do with Bella's plan. So she has been cautious about Nika. Since Nika already knows that she's not an airhead, she didn't try to play one with him. However, she has been trying to find out if Nika is a nice person or an asshole and maybe how much he is involved in Bella's plan, trying to find more clues about their game and why or how they are trying to use her.
I haven't played the ch5 beta, so I don't know how much this story has progressed since the last chapter.
I think that depending on the impression she is going to get about Nika, she can become either a friend and an ally, a neutral "friend" who simply won't play their game or get involved in it or she is going to teach them a lesson of some kind.