@1234muse
I would assume the best method would be for him/her to get some really close allies within the order. Someone who could speak on their behalf since clearly she sides with them more than the vampires at the moment. Plus she likely would be their strongest asset, as long as a stable supply if blood is provided that is.
Then again, she is completely neutral. Half of her despises vampires, but being one herself, she also seems to struggle with thinking much more of humans than just blood bags too. Kind of like she'd rather side with humans, or be just left alone. But if it comes to it, at least humans can still become food for her. She loaths her "mother", but may not be able to go against her too much if at all.