I have been reading Eclipse and I see there is a mystery about a certain entity stalking Bella. I see werewolves, I see vampires, is it not right to expect witches to make an appearance. But Victoria could have a helper….And with Edward’s specific talents she would be well advised to get some serious help.
There can’t be any normal supposition against supernatural characters. In fact, there is a rather amusing part in the books where Jacob tries to make the case to Bella that being Edward’s girlfriend isn’t natural. But the point Bella hints at is that neither is Jacob.
So it may be the case that a witch can be used by the vampire tracking Bella, knowing that her protectors are wolf and fang, but cannot be expecting a witch and those kinds of powers. The fact that Bell’as stuff is stolen point to a spell…