"There's plenty of things that haven't changed. People still eat food and wear shoes and so on."

"I guess that depends on how Bella feels about driving us back to the butcher's shop. Bella?"

"I gotcha covered."

"...You all right?" asks Miles.

"I'm correct in assuming that 'clear' means you're pretty damn sure that is an innocent random teenager who thinks she's my sister?"

"Yes. It's still possible that she might be putting up a front, but most people can't actually put up a front deep enough to fool me. She's either an innocent teenager, a non-innocent who has a very complete 'innocent teenager' personality to draw on, or using undetectably subtle mind control that I have no hope of ever defeating. And if it's the last one and it's failing to work on you like the memory alteration did I would've expected someone to notice - you, me, her, Mark, somebody."

"Nah, I would've believed she was real too. DDR," mutters Bella. "With the arcade prize bracelets to match. So, no, I'm not all right, that's not all right, that's really fucked up."

Mark and Miles exchange a glance.

"It's entirely possible there is something at work which legitimately has to go, on which her existence is ontologically dependent," says Bella, ticking off fingers, "if your hypothesis is right she might be sustainable in principle but have something nasty after her which I will have to fend off, either me or literally everybody who has ever had the slightest counterfactual causal contact with the possibility of her existence has been mind controlled, and even if this is otherwise some completely benign gosh-leprechauns-are-real-and-they-give-you-sisters thing and nobody is going to die or be further mindwhammied, at some point I am probably going to have to explain to her that from the perspective of inside my head she's brand new and I don't think she'll take that well!"

"Yeah," says Miles. "Uh. ...I don't have any advice as such on the topic, but I'm sympathetic to the situation of suddenly acquiring a sibling you weren't prepared for."

"Yeah?"

"I'm the product of a clone substitution plot," says Mark. "I was supposed to impersonate Miles and kill his family to cause political instability on his home planet. We met, oh, a few months ago now; he did not previously know I existed."

"Wow, that sounds really awkward too."

"Miles handled it admirably."

"But yes, it was very awkward."

"In the nobody's-dying, do-not-have-to-prevent-more-people-from-getting-surprise-mindcontrol-siblings scenario what actually concerns me isn't that she exists but that she is going to expect some shared history with me I can't hold up my end of, which seems like the part you would not have run into."

"...It's... sort of similar to a problem we've had," says Miles. "Mark knows me a lot better than I know him. What with having been forced to obsessively study my life history. But yeah, it's not quite the same thing."

"Yeah," agrees Miles.

"Welcome. Anything else you need from us in the near future?"

"Probably not. I'll see if I can conveniently nab you a phone though."