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—
"The other thing is that, erm, well a few things. The 'evil' thing is, like I said, mostly something of a, a shield. Because I'm in general terrified of fairies, which is perhaps not an entirely reasonable feeling but." Shrug. "Dangerous may well have been enough to produce the relevant emotions, however. And the other thing is that I—didn't have much of a plan, yet, but I expected I'd remove this from my brain when I needed to, once I started formulating said plan. So, I don't want you to have the impression that I didn't know this would have to go sooner or later. And anyway, all that said, you're still right, and I'll—excise this from my mind."
Shrug. "My interactions with fairies for the past fifteen years have been limited to books I got and what my mother told happened every time she visited the library. Being insistently offered food or asked for her name were pretty common themes."
"The fairies who didn't want to catch her would have much less reason to talk to her."
"Yeah, but fairy fiction was a thing, too, though, when shaping how I thought about fairies. It's... I don't know, a bit... sad, to me, the way fairy relationships must work, with the prospect of being taken as someone's vassal kinda looming in the background of every interaction. Or maybe I was just projecting a lot onto what I was reading."
"No, that's a thing. A lot of us just live alone. Some people find someone they like and just give up their name so they can stop worrying. Some people get a thrill out of playing with it."
She sighs. "This is one of the things I'd like to fix. There are—so many ways to interact with people. But I also don't really think it'd be fair to take the thrill from those who enjoy it, ideally I'd find some solution to make everyone happy..."
"I think the ones who gamble with it are ultimately rationalizing, I don't think they'd seek out that kind of danger if it didn't exist to start out."
Last safe house! Another one with two stories, a road is visible in the distance but most of the surroundings are steppes.
"Seeking thrills because or while they know they're safe, yeah, sure. Remind me to take you to an amusement park sometime."
"But I'm not really sure it'll possible to simulate that thrill safely. I might have to actually introduce amusement parks to fairyland. Roller coasters probably aren't as thrilling when you can fly, though..."
"If they simulate flight for mortals, I don't imagine they're as good as the real thing, no."
"No, not flight, they're... basically very twisty rails and there's a car on them and mortals ride that car and the car typically goes very fast along those twisty, loopy rails," she says, drawing an imaginary roller-coaster's path in the air with a finger.
"I think the fastest one around might get to over one hundred miles per hour? But fifty might be a more typical number."
"Yeah, humans can't. The fun part of roller coasters is supposed to be not just the speed, though, there's also the loops and falls and twists which are typically not part of our day-to-day life even in faster vehicles."
"One can do those flying if one wants. I don't think you're going to sell many fairies on amusement parks."
"That's not all amusement parks have, though! And I'm sure the concept can be imported and adapted to the kinds of things fairies would like."