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—
"Not anytime soon, the Sun should last another five billion years and by then humanity will have either wiped itself out or colonised other planets. The universe as a whole will also eventually end and that will take even longer. This isn't something I'm really worried about right now. It's just—also a consideration, plus colonising parts of the infinite plane that is fairyland is much more easily feasible than doing the same to the infinite three-dimensional expanse made mostly of uninhabitable emptiness that is the mortal universe, not to mention all the benefits mortals could reap from learning how to use sorcery in the systematic way they do and the benefits fairies could reap from the stuff mortals know how to do, and—" She cuts herself off. "Dreams of a perfect future aside, just from the resources and mortality points of view figuring out some arrangement where mortals would have access to fairyland and vice-versa sounds like something that ought to eventually happen."
"But first you need to deal with the thing where it's not really safe for mortals to live there without fairy protection and not that safe even with."
"That depends on how we go about it, large-scale security systems are a thing, even if mostly a thing only governments have access to, but I don't think it's conductive to the kind of environment I want to have to shoot fairies out of the air whenever they come too close."
"And in any case this strikes me as the kind of thing the Queen would object to, even if we found a way to do it safely and spread that information in a controlled way. And using the resources at the Queen's disposal would only make this easier and less likely to fail horribly."
"On the other hand having a mortal country in fairyland would make storming Queenscourt easier. Which is why I asked how large her reach was, if we manage to get safely outside it and play this right it might actually be easier to do it that way around."
"I think it takes something like fifteen hours? Maybe twenty? To cross the globe with a plane, but planes need significant infrastructure, not to mention special training to be piloted. ...maybe not significant infrastructure, depending on the plane, private jets, hmm..." While she says this she looks up stuff like the circumference of the Earth to give a basis of comparison and shows it to Promise.
"We'd need to get farther away than that to be really sure of not being discovered," Promise says.
"Yeah, I expected so, the problem is just how much farther, and whether it's feasible to do it. Travelling in fits and leaving gates where we stop is an idea, but the unpredictability of fairyland terrain can be a problem when it comes to landing the plane."
More webpages to aid in explaining! "They need a fair distance of reasonably flat ground to take off and land, and they can't hover, they must be moving to stay in the air. Helicopters can hover and basically just land verticality but are much slower."
"I don't know how different types of planes deal with different types of terrain but I'm pretty sure fairyland varies enough to eventually outclass any plane I get my hands on if we fly far enough, so this would need to be played pretty smart if it were to work at all." Pause. "Like everything else here."
"That's for the future, anyway," she shrugs. "For now, we get to spend hours watching Thorn and Blossom sleep."
"Probably a good idea. I kinda want to, too, but I'm not sure I trust Yellow enough, and I did take a nap not too long ago."
And Mortal boredly watches Thorn's sleep, and eventually confines that window to half of her screen and starts looking stuff up about planes and landing distance and conditions and fuel consumption.
Promise is awake before Thorn is, although not before Blossom opens her eyes and frowns furiously into space.