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—
"Okay, now try locking it? Although, will you be able to reopen the exact same door if you do?"
Sadde gets the key and plants a kiss on Cam's cheek, successfully not getting superglued to his face.
"...okay, that's unexpected. I can summon you even with a locked door." He reopens the door he just locked and starts dismissing Cam.
"Well, apparently it works differently. Maybe I just can't be dismissed from places outside my usual universe range but summoning tries a little harder?"
"No, I managed to dismiss you when the door was unlocked. I think maybe the dismissal is more... local than the summoning, somehow? Like we have to be sharing space, or something?"
"That would make sense. Dismissal's normally done from nearby and summoning from, well, far away."
"Yeah." Pause. "I wonder what happens if your summoner dies while you're in different universes, if voluntary dismissal doesn't work across. I definitely don't want to test that one, unless we find someone with a terminal disease who'd like to try and a daeva who wants to risk never being summonable again."
"Those... yeah, those would be the conditions. Although a lot of demons don't go in for summoning. It's sort of a weird hobby."
"Well, then it might not be that hard to find one. We'd still need a portal to the mortal world, though, or for someone to summon you ungagged so you could suggest this, or something. Probably not worth it."
Shrug. "There's one other test I wanted to perform, but we'd need someone else here, maybe two people to make sure. Preferably bound daeva."
"I want to see whether summoning works when neither of us is in Hell. The experimental setup I have in mind is I open a door here, someone else holds it open, then I go through the door and open a second door somewhere else, go through that door and open a third door somewhere else. Then one of us goes through the third door, the other of us locks it and gives the key to the person holding the second door, that person locks it. That way we're both in two different universes and completely disconnected from Hell. Then I try to summon you. The thing where dismissal doesn't work apparently doesn't care whether I'm in Hell or not, since I was when it didn't."
"Involves fairly high trust of the daeva and not super great infosec."
"Yeah, but I don't see another way to test it, so this might be another shelved test."