By jove, you guys are giving her way too much credit. She treats Vera the way she does because her brother has shown her that no matter how proud a person is, they can be whittled down to nothing. The moment Vera gave up his pride and started following her brother's orders (licking the dropped wine) is when she realizes this truth and her sadistic character awakens (as seen by her evil grimace). She, too, takes pleasure in torturing proud people until they abandon their pride.
She doesn't carry romantic feelings toward Vera, she just enjoys hurting him because he's naïve and prideful, the perfect target. Heck, she's already treating him like a subhuman by stepping on his face after asserting dominance. The only thing she respects about him is his combat prowess. That you all are still giving her the benefit of the doubt at this point can only be a form of coping.
I'm personally quite interested to see where this will go, considering we don't get many asshole leads quite like this one.