Yeah, she's a very skilled passive-aggressive manipulator. I don't think Anthy had no will, just that she wished she didn't and tried to make it go away.

In a lot of ways she reminded me of a child abuse victim: devoted to the person causing her suffering and trying to please them, and at the same time hating and resenting everything and acting that out. We see her use her powers to manipulate people, for revenge and for convenience, but never directly to help herself or spare herself pain.