"Well, I suppose if the mortal world is only one of those then the others might be any which way about sorcery, but I'd still have some trouble getting food safely outside of Fairyland."

"Well, I can certainly drop you anywhere in Fairyland. I'm curious how food synthesized on the Bus would interact, though I suppose you won't want to test it."

"If the Bus is a person it would presumably count as her food."

"That would seem to follow! Though I don't actually remember where I got that granola bar, so I'm afraid the question may already be moot unless a piece of food can only count for one person. Also, she can't or won't talk to anyone other than me."

They've gotten far enough from the house by now that it would probably be safe to set it on fire.

"It could theoretically count for more than one person but it came straight out of your hand and nobody else who was involved with it is specifically likely to try ordering me around, especially if the bus won't try to talk to me at all."

She looks over her shoulder and the house goes from quaint to flaming slag in less than a second.

"I haven't known her to give anyone else more than an eye-roll in centuries."

When Promise slags the house, she adds, "My, what interesting magic! I can see why you'd want to hang onto that. And generally learnable too, from the looks of it."

"Yes. You can tell that by looking?"

"My species can see a lot of things. Your magic didn't seem to be attached to you in the way, say, orders are, so it's less likely to be a matter of being the right species."

"Mortals can learn sorcery, yes. I don't know about whatever you are."

"I'm a Time Lady. So called because we were the first species in my original universe to invent time travel, and whoever decided they had the authority to name us all was excessively pompous."

"You have time travel?"

"I certainly do! Silly me, I thought I had mentioned it. Yes, the Bus can go anywhere and anywhen in any of several thousand universes."

"How does that work with travel that would alter the past?"

"I can go over the math with you if you like, but the short version is that whatever you do turns out to produce a single consistent history. Maybe you fail to do whatever would have changed the past; maybe you succeed but it turns out whatever you did was part of the history of the events you remember. In a few extreme situations, it's possible to split history into two different timelines, but the Bus is quite capable and can reliably avoid that sort of thing."

"Oh."

"Quite."  

It doesn't sound like she wants to talk about it.

"Well. Maybe it'd be safer to take a cutting of my tree from years ago when it was more definite no one was staking it out, and then drop me off in the future far enough that my name will have been forgotten."

"That, I can certainly do. Not much farther from here to the Bus."

"Thank you."

Then they can walk in silence until they reach a tree that looks slightly off somehow. Corundum smiles as she approaches, and the tree shifts and warps and suddenly there isn't a tree at all, but a yellow school bus distorted into the shape of a tree trunk and with branches growing out of it. And a pair of large, friendly eyes and a smiling mouth.

...okay. "Hello."

The eyes blink at her. "All aboard!" Chirps Ms. Frizzle, climbing into the Bus as the door folds open.

Promise goes in.

The inside looks even less like a school bus than the outside. There are padded benches, there's a large control panel with a great many mysterious buttons and levers and a large chair in front of it, and that's it for the resemblance. The rest is a large circular room that could not possibly fit inside the visible outside, crowded with posters, plants, rocks, unidentifiable things in jars, machinery, a skeleton on a stand wearing a vest and top hat, and a tank of small glittering fish. Several other doors are visible around the walls.

"Welcome to the Bus! The bathroom is through there, the food replicator is that green box--oh, and she tells me that for fairy purposes, the food from the replicator belongs to whoever was operating it at the time. Now, where and when shall we go first?"

"My tree. About fifteen years ago, let's say."