Originally Posted by
Altima of the Gates
Honestly, the two of them seemed to get along pretty well in Hollow. She never wanted the Grail except for being with Kuzuki anyway, who didn't have enough power to sustain her, and who she didn't want to risk ruining his daily life by leeching people dry (which is why she only leeched them until they fainted). Zouken caught her off guard because he was out of the picture in HF, now that she is aware of him, he's screwed.
With this she has no reason to jump ship. Her master is stoic, powerful, young, and female. Getting rid of a bug or two would be nothing to her, in deference to the good luck she has that she is with someone she doesn't have to manipulate. She is free to live for love, without relying on using magic to be the witch she loathes being.
Plus, with this partnership, she'd be able to see the Grail is pretty much cursed(though, iirc, I think I heard somewhere that she could do something about that). That pretty much annihilates the reason for them to fight except to protect themselves or someone else.