Sadde's running.
Not for any particular reason, just because it's faster. He's been meaning to go to one of the capitals for a bit and now, he supposes, is as good a time as any.
And eventually he's not running anymore, because he's close enough to civilisation that someone might spot him. Not that he wouldn't be able to notice them by scent before they saw him, but still. And as he makes his way to the Norway capital at this more leisurely pace, he notices the tiny, shiny key. He walks towards it and picks it up and immediately notices just how magic it is. He can tell by the way the key feels like things, and different things depending on where it is.
He verifies that what the key feels like is consistent in absolute location by waving it around a bit and seeing that the same place always feels the same. "Huh," he murmurs to himself.
He straightens up and thinks. The first obvious thing to try is seeing whether it opens any doors—a universal skeleton key sounds like the kind of thing a magical key could be—but the second obvious thing can be tested right there and then. He pushes the key into thin air with some purpose, as if he wanted to unlock an invisible door, and then turns it, et voilà, the faintest of door-shaped outlines appears before him.
He locks the door, and it disappears. Unlocks it again, and there it is. So he pulls it open and sees—
"Once you have cannibalized a set of wings from a basement dweller of yourself you will be able to pass well enough to go visit demon physicists. I'd be surprised if the idea were completely novel to the world but I haven't studied that kinda thing very much so far."
"I have my medical and engineering quals up to the highest levels available in organized demonic education, and I play the violin, and I have learned several languages the long way, and I can program, and I keep up with media, mostly human some demon smatterings of angel and fairy and Limboite."
"It's kinda weird that your universe's afterlife isn't actually an afterlife and just happens to sometimes collect dead humans and also has its own functioning society and such."
"I mean, Limbo only collects dead humans and it has a society too. You show up in Limbo and you have to learn the local weird pidgin language and learn how you're supposed to get water and, if available, food rations."
"Yes, that is weird as well. And it's even weirder that there are only humans, does that mean your entire universe is devoid of other sapient life?"
"Not necessarily. But if there are aliens, then they either don't go to limbo or the daeva realms, or they do it so unfathomably far away that we haven't run into 'em here nor there."
"Huh, yeah that's actually pretty reasonable, if all of those universes are infinite."
"Yeah, sure. I don't actually have a basement. Uh, do you actually still run on a genome?"
"Okay, if you want a genetic match - do you know your chromosomal sex?"
"XY, and yes a genetic match is ideal, vampire venom tends to burn other vampires, I assume that's got something to do with genetics and who knows how wings without my DNA would react, my body might just end up melting them."
"Okay, so I'll make a male basement dweller in case it's complicated in some way, anything else I should know?"
"Okay. Lacking a basement I will just stash it in the closet." Cam goes to his closet, makes a squishified vampiric winged male Sadde basement dweller curled up in it, and leaves it there.
"...it might be. See if you can appear a vial of my venom? Glass, venom doesn't corrode glass."
Cam makes one. "This doesn't necessarily mean there's nothing irreducibly magical about it, just that its existence as a substance isn't magic," he observes.
"Like, if I try to make a magic rock, and I try in an insufficiently conditional way, I might wind up with a rock, just not a magic one."
"Oh. Hmmm. Well, I guess it doesn't hurt to be sure. Can you make me a syringe?"