"Harmonics are an invisible feature of places," Promise says. "They vary, usually continuously but not always and at various rates. Sort of like... ground level. Except in three dimensions. They're one of the things that matters for sorcery, and when they are all the same it's a lot easier to take them into account. I don't know why mortals wouldn't already have sorcery if it's flat everywhere. Maybe it's only flat some places."

"Or maybe sorcery can only be done by a fairy, or in the presence of a fairy, or only learned likewise, or maybe there's some less guessable connection to the very weird fact that fairies have all heard of a mortal world where they think sorcery doesn't work but this mortal world, where sorcery does work, has only heard of fairies as fictional beings with some of their most relevant properties omitted. It's fascinating and I'm fascinated but before I get too far into that, I want to talk to you about your immediate plans. How much interest do you have in becoming unspeakably rich via the sale of interstellar portals?"

"I... kind of want to spend at least a month living an extremely boring life in my own tree putting my psyche back together. But after that it sounds more interesting than most things I might be doing in Fairyland."

"Yeah, that's fair," he agrees. "In which case I guess the first problem to be solved is getting you a cutting of that tree?"

"Yeah. The problem with gates is that they can take any amount of time to settle. Days, sometimes. And they start open. If I make one, and it settles while I'm asleep, there will just be an open Fairyland gate to right where he'd be looking for me if he looked."

"...That's... potentially solvable," he says thoughtfully. "And, um. I feel like I owe you an explanation of why I'm so interested in solving your problems - I mean, I'm sure you've guessed that I'm very excited about potentially learning sorcery, and it may be apparent that I'm of a problem-solving nature in general, but there's cultural context on top of that."

"It's... I might make a mess of this, I apologize, I'm using up a lot of brainpower on name-related censoring and trying to avoid saying things that might be orders, but - the word 'vassal', on this planet, refers to a cultural phenomenon with no magical enforcement whatsoever. And under that system, having a vassal comes with responsibilities. I take those responsibilities very seriously. You're obviously coming from a vastly different context, but as far as I'm concerned, for as long as you are magically required to obey my commands I have a personal duty to see to your safety and comfort."

"I know, but I'm being paranoid about it anyway because my level of discomfort with this entire system is extremely high."

"Oh." Pause. "What was your idea about the gate problem?"

"Oh. Set up the gate in an uninhabited location that would be prohibitively difficult to leave unassisted, and monitor it remotely in case anybody comes through. Then if we get any unexpected visitors they're alone on a deserted moon with no idea where you are. And you can check it at your leisure with your handy access to mortal technology. It'd be a little expensive to do it that way, but if you verify that the interplanetary portals are possible and express an interest in making some eventually, I, um, happen to be childhood friends with the emperor of this planet and could probably get him to front some extravagant aid if it means you start with us when you do get around to selling portals."

"Difficult to leave how...?"

"I guess I should check my assumptions. How high can fairies fly, and what if anything stops them from going higher?"

"If we go up too far the air gets too thin for wingbeats to do anything. I'm not sure if anything would stop the ones who can teleport. I guess they might pass out eventually."

"...There's ones who can teleport?"

"Crystalswifts. They don't go very far, but they could probably outpace falling speed if they tried."

"That sounds like a deeply inefficient method of space travel," he says. "If there aren't any precise long-distance teleporters, sticking the gate on a moon will almost certainly work just fine. Space is big."

"It must be, if those pictures you showed me were to scale."

"The solar system one actually shrank the distances between planets by a lot, proportional to their size," he says. "Because when the scales are accurate it can be difficult to have more than one planet in view at a time, even in the same system, the littler ones would be the size of dust motes before you could fit them all in a display area together. Space is big."

"Anyway - I don't object in principle to making gates around place to place."

"Okay. Then if we decide on a solution to the tree thing that requires lots of money, I can politely ask the Emperor for lots of money, and he'll want to see proof that you exist and can do magic of the relevant type, but I'm pretty sure he'll come through once that's established."

"Okay. ...It probably is safe just to wait a while until he won't be likely to have the tree staked out and then do a tiny gate, though. Especially if someone can keep poking a stick through the area to check if it's open all the time. I could also maybe just make the gate to the inside of my tree, I think with a little finagling I could get it to extend a plantable branch through the inside. Nobody can get into my tree if I don't let them and he never made me let him."

"That seems simpler all round," says Silver. "What do gates look like? How frequently and how consistently would you want it being poked with a stick to ensure that you caught it soon enough after it opened?"

"They don't look like anything. A minute or two, I guess."