It started with Scar, then the Oncler (she actually went as this for Halloween 2-years ago), the Joker, Gaston, Hades. And now thanks to the Disney's Descendants she loves Maleficent, Evil Queen, Cruella Deville. At this point if she watched Game of Thrones she would root for Cersei Lannister.
Should I be worried? I would be if she didn't have such a big heart. She doesn't replicate their behavior. But she does have a root for the underdog thing. I suppose it is not a bad thing that she can see that things are not black and white in this world. People are complex and everyone can have a good side. She doesn't judge others the way the world judges them.
Frankenstein's Monster was not meant to be bad, but the world saw him that way.
But this stops when she becomes a teenage. No BAD BOYS!