The plan is refined and strengthened, contingencies are set to deal with various ways Thorn could've strengthened his defences, Mortal receives a very interesting email concerning one of their mother's contingency plans—namely that her assets have all been either frozen or transferred to Mortal themself, so Thorn doesn't have access to them -, and when Mortal and Promise judge there's nothing more to be gained from further planning they (eat dinner, sleep again, have breakfast, go over the plan once more when it's not completely fresh in their minds so they see if they come up with anything new, purchase Promise a mobile phone and a power generator to charge its battery in fairyland, eat lunch while Mortal teaches Promise how to use that, and) part ways.
On this side of the veil, Mortal gets to work. The first step: getting at least two safe houses, one for their HQ and the other for contact with the place near Thorn's court. They end up getting five, for redundancy's sake. The main HQ is near Seattle, the other four safe houses are in Greece, Russia, Japan, and Argentina. That, and getting the necessary existing equipment, is the easy part—you end up with contacts of the relevant sort when the bulk of your wealth comes from the kind of thing you can get with sorcery. The hard part is getting the various specific bits of technology that don't exist yet, including the the many types of trap and ammunition they'll need. Processing fairy voices with software turns out to be a dead end—apparently they're weird magical superpositions of sounds that make software go ?!?!?!?!?—but everything else, as agreed upon, can be made to spec nicely enough.
It'll take a couple of weeks beyond the one month for everything to be ready. Mortal hires someone who talks very fast.
And after the ball's going, there's not actually much for them to do with their time. They fret about details of the plan, order more redundant pieces of stuff (especially the to-spec stuff, not being mass-produced means they'd better have a lot of it to start with in case anything goes wrong), and have various antsy and anxious and calm and relaxed and terrified and panicked moods. A month is a long time...
At one point it occurs to Mortal that Promise might've decided to run away and not help, and then they'd never see her again and that would be terrible, and why would it be terrible anyway? It's just some fairy, fairies are evil, one must remember that. Even though she wasn't, of course, she was smart and resourceful and moral and ridiculously hot, and if they never see her again she'll never order them again and the tingly feelings won't ever happen again. Except what the heck, what are they even thinking? The answer, of course, is that they want to see Promise again. Why? To save their mother, of course. The only reason being ordered like that felt good was because Science. Of course. Of course.
The month passes—
Promise says, "What steps would accomplish that goal?"
"Collecting the names of my major vassals, having Rainfall deactivate the noise traps and me cut off interfering actions from the other top sorcerers, and not making any mistakes."
"Must whatever-it-is you need to do to cut off interfering actions from the other top sorcerers be done by you, personally?"
"They're probably authorized to interfere arbitrarily with anyone else who shows up and probably have deadman switch setups," mutters Promise.
"Yeah, I'd expected so, was just checking. Well, Thorn and his people are only a few minutes late, we should probably start taking those steps. I think micromanaging him isn't likely to be very helpful, though, we should probably give him a more general order like 'do whatever needs to be done in order to ensure Promise and I have full control et cetera et cetera'?"
"Pluses and minuses to micromanagement. Depends on how likely we are to make a mistake that matters."
"We could start with a blanket general order and abuse stuff like 'sincerely' and 'best up-to-date model' on it and then give other orders as needed?"
"I think if he gets half a chance he'll find a way to startle us and make you say something stupid."
"Is that an argument for or against micromanaging? And besides, you can man the console and give him orders, I am not about to let pride get in the way of actually succeeding."
"For, if you can do well enough when not startled to prevent him from startling you; against if you can't."
"I'm pretty sure I can, unless what you have in mind when you say 'startle' is significantly different than what I do. And maybe we should get Thorn's entourage moving again and discuss while they do it, there are still a few hours before they'd arrive, and as far as all other courts know everything's fine."
Promise nods. She speaks into the mic, crisp elaborately airtight sentences. The fairies get up into the air again.
"And while we're at it, please give us the names of all your major vassals." Once again, the 'please' is merely decorative. "And tell us where Rainfall is."
"Expand the definition of 'major'," Promise says, after counting them on her fingers.
Thorn grits out a few more names and Rainfall's location.
"What should our immediate next step be to accomplish our ostensive plan with respect to you, your court, and your vassals according to your sincere best up-to-date model of the world?"
Promise groans. "Describe a plan which you sincerely expect is the most likely of plans you might invent to be effective by our lights at our goals without inconvenience to us."
Thorn doesn't have a snappy comeback for that one.
"Always answer questions directed at you by Promise or me according to your sincere best up-to-date model of their spirit as intended by their composer. Never lie to us, mislead us, or omit facts which you sincerely according to your best up-to-date model of us believe we would find relevant when giving us any information, prioritising things by how urgent they are."
Thorn is silent. Promise barks back the orders outlined in his plan at him. Fairies fly on.
"This somehow fails to be reassuring, relieving, soothing, or in any way not nerve-wracking," he comments.
"Yep. It is possible you should not deliver him orders," Promise sighs. "You really aren't very good at it."
"Like I said, I will not let my pride stand in the way of this being successful, my comparative advantage is not rule-lawyering."
Nod. "You're better at it than Yellow and Verve's hostile, so if I wind up asleep or something while something urgent happens you should do it rather than delegating, but I'll handle it while I'm available."
"Well, given that when this started I was apparently worse at it than Yellow, I'll take that as a win."