"Thanks. We'll be around, I guess, here or at the school."

"Yep."

"See you."

The books do not seem to know what the fuck, or at any rate they don't have better guesses than 'a wish demon, maybe, but who the heck would wish for this'.

Giles spends the next day interrogating every available book. Unfortunately, he just doesn't have enough information to ask the right questions. Maybe-a-wish-demon remains the best going theory.

"Is there a wish demon hangout somewhere I can go shake down for confirmations-or-denials...?"

"...I really wouldn't recommend it. Dealing with wish demons is a dangerous business. Their power is usually limited to carrying out wishes made by mortals, often ones who have no idea there is a wish demon present, and only within a specific domain - vengeance demons are the kind I'm most familiar with. But that would still mean that if you annoyed a vengeance demon, she could erase you from ever having existed the next time someone made a wish of which that was a plausible side effect."

"Bleah. My powerset is stupid, Giles."

"I can't argue with that."

"What do you think of Miles's idea that I was supposed to remember her, she's new, and somebody wanted me to protect her?"

"It... seems plausible. But I have no idea what manner of wish demon would take that sort of thing as their domain. And if it wasn't a wish demon, I have no idea what it was."

"Witches can get really freeform, right? And scale things up if they work in covens?"

"Yes. But who or what did a large number of powerful magic users want to protect so badly that they turned that person or thing into your sister?"

"No idea. I'm not sure to what extent it makes sense for her to simultaneously be some thing. Is there a class of things that takes well to being turned into people?"

"Not as such, no... if she was a person beforehand, though, she is now a different person. At least, so one assumes. Your vampire friend indicated that she didn't seem to have any awareness of her circumstances. Who could want to hide badly enough to erase their own memories, their own identity? And what would she have been hiding from?"

"Any prophecies coming due?" Bella wonders. "- Or it could be something weird and convoluted, like, somebody's geased to protect so-and-so, but doesn't want to do that anymore, so they find something that is technically protective and do that..."

"I can double-check the prophecies I know about, but I don't recall any that sounded remotely applicable."

"I don't know her well. We've spoken a few times. I... have no idea what you should say, I'm sorry."

"Okay - how do you remember me talking about her."

"You... seemed to like her, and, and trust her. I'm - I haven't been taking notes, you understand."

"Yeah, but I haven't even been taking memories, so."

"Yes... I'm sorry," he says helplessly. "I've never had occasion to analyze your interactions from the perspective of 'how would Bella's sister react if she found out Bella no longer remembered her existence?'."