"Is your instinct that because you remember meeting some girl who's, how old is she, who has sleepovers and shit, or because that is the actual better part of possible demonic shenanigans."

"I'm legit asking, you'd know and I wouldn't, but as the person here who does not remember some harmless how-old-is-she having sleepovers... reminding you to think about it."

"Patterns of demonic activity are what I was thinking of. I would expect... aesthetic differences, nothing I can easily pinpoint... if she were the source of the problem."

"Mm. So obvious options seem to divide into 'here's your ride home, Soph, I will be at the library all night, Slayer stuff' to postpone diagnosis; and 'Soph, you may or may not be demonic, please come to this not-Charlie's-house location for analysis'. Is there any sort of analysis to do?"

"I would be wildly out of my depth trying any kind of direct magical examination. The best we could hope for from that is the chance that she might, ah, reveal herself and attack, if we tried it."

"What could anybody possibly have to gain by giving me a sister or making me forget one?"

"I have no idea."

"...If you remembered her," says Miles, "you would value her highly, I'm assuming. Someone could have had someone or something they wanted protected at all costs by a powerful force."

"But I don't. Everybody remembers her but me. Phone, Watcher, ray gun vampire. - Giles, did you catch that?"

"Catch what?"

"Miles speculates that if I did remember her I'd value her and someone could have wanted something protected by, well, me. But I'm the gap in the memory revision, if she's a construct and I'm not just the sole victim."

"Yes... I'm not sure what to think."

"Analyzing purely from the motive angle, it really looks like someone tried to get themselves or someone else under your protection and failed," says Miles. "...It terrifies me to even suggest this, but under almost any conceivable circumstance in which we have any hope of handling this situation at all, I bet I could figure out whether she's complicit by talking to her. I have a finely honed sense of people's motives."

"...Well, I could call back and see if she wants to meet Ray Gun Vampire."

"Sure, why not, don't let 'em eat me."

"I'm not expecting them to eat anybody. Remind me what address you're at?"

"22 Orchard, Sam's place!"

Miles, meanwhile, takes psychologically soothing deep breaths.

"...Well, if that's what you think best," says Giles. "Good luck."

And Bella drives to 22 Orchard.

A girl who strongly resembles her traipses out, interrupted-sleepover-accessories under each arm. "Hi Bella! Hi ray gun vampire and creepy house vampire I know your names start with M but I can't for the life of me rememb- oh now I remember one of you is Miles, how'd I forget that, it rhymes with Giles."