I don't think she's evil, but I do kinda think she's a wacko. She's learned how to hide it now, but remember back in the day when she was suicidal, kissing her brother inappropriately, straight and then gay and then straight again, putting Billy Bob's blood in a vile around her neck.. And that's only what we know about! She seems to be very obsessive, but fortunately she's put that obsessiveness into aiding third world countries and children.
Or maybe she's just an alien. If so, her alien features are slowly yet surely starting to expose themselves.