"Don't worry about it," he says cheerfully into the phone. "Bye." And he successfully disconnects the call.

"The fuck."

"I knew Miles hadn't just invented you a sister out of whole cloth and I apologize for not voicing my suspicions sooner," says Mark. "I have no idea what the fuck, however."

"I don't have a sister! I've never had a sister!"

"I'm perfectly willing to believe that you didn't have a sister before, but one appears to have been inflicted on you sometime in the last few hours."

"Or something. In context she's way more likely to be some kind of weirdass demon. With... sloppy memory alteration habits?"

"The memory alteration caught Miles with a subtle enough touch that he'd only heard her mentioned once offhand and not by name. I'm not inclined to call that sloppy. Something else seems likelier, though I don't know what."

"I suppose it's possible I had her and then forgot her, but - but I remember a really coherent entire life without a sister. Renée went househunting in Jacksonville and picked a two-bedroom, so I could visit, she kept a lot of my kindergarten drawings and I took all kinds of creative license with how to represent the concept of divorce but I never had a sister -"

"Verify whether your parents remember coherent entire lives with the sister included?" he suggests.

"I'm really not sure how to call my parents and discreetly confirm that they only had one kid! I guess I could mention 'Soph' vaguely like she was a school friend, see if they grab it..."

"Yeah, that'll work if you can swing it," says Miles.

"But first I want to talk to Giles in case he goes 'oh, that's the Thusandsuch demon, it works like so, kill it on a waxing crescent moon by making an accurate representation of your family as it was when you were in kindergarten in crayon and burning it' or something."

"Reasonable."

So she pulls over and calls Giles.

"Yes?"

"Do you by any chance have an off-the-top-of-your-head diagnosis for my having a retroactively inserted sister, programmed into my phone, expecting me to pick her up from a friend's house, and turning up in other people's memories of my offhand remarks, who I can't remember having in the first place?"

"It's entirely possible that's what I need to hear right now but I swear to the Powers that Be In My Bedroom Sometimes that I don't remember her! Where would she go? Is she expecting to go to sleep in a mysteriously appearing second bed in my room or did Charlie's house morph to accommodate her or did my address change?"

"I believe you've mentioned said Powers waking her up..."

"Christ. Okay. What could've done this - either which way?"

"Deleting a sister from your mind: Powerful magic, I haven't heard of anything specific. Adding a sister to the universe: Much more powerful magic, I haven't heard of anything specific but it would be beyond the reach of most minor gods. There are classes of wish-granting demon that have effects this sweeping, but if this is a granted wish then I have no idea who could have wished for it... it does seem similar to a wished effect in some respects. A single central change with, with comprehensive secondary results. But in that case the only people who remembered the previous reality would normally be the person who made the wish and the demon who granted it, and I must assume you're neither."

"I don't remember wishing for a sister. I've never particularly wanted a sister. Do you remember me liking having a sister?"

"Yes. I've never had occasion to suspect that you were anything less than fond of her."

"...I don't know. But my instinct is that the latter is more likely."