Bella slips into the school by a side door; she just saw a thing and she thinks she's seen it in a book before and thinks it's supposed to be mostly harmless but before she wakes Giles up over probably nothing or kills a likely neutral demon she wants to check.
And she pushes into the library.
"Thanks. Take care. If I come back and find you've been killed in the line of duty, I will look into resurrection."
"Aww, thanks, although please consult people on that, I hear it can be a real disaster handled improperly."
Then Bella gets a call from the airport.
Miles is looking slightly weathered but intensely happy. He waves when he spots her car approaching.
"Turns out they don't offer bulk pricing on souls. Since Mark is getting by just fine without his, we decided not to bother."
"All right then. If he suddenly sits bolt upright in bed and realizes that he has lost his love of classical music and needs it back I will tell you to take a taxi if it is an inopportune time."
"The discovery of wormhole jump technology in the early 2200s pretty sharply separated human history into a Before and an After. Colonizing other planets wasn't a feasible enterprise, and then it was."
"Not in sufficient detail to recreate it, unless you happen to know a half-dozen geniuses we can consult with."
"Will do," Miles says cheerfully. "So how've you been while we were away? How's your sister?"