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—
"Well, then. I think we can at least tentatively conclude that two spots feeling the same doesn't mean they lead to the same general location."
"Goood question. We could try opening a bunch and seeing how they differ and whether we can find a pattern?"
"Sounds like a plan. Only one key and you've got the memory and precision of movement, you want to do that while I brush up on all the languages I know by not-magic so they don't rust?"
He doesn't whine (out loud) even a little bit at the prospect of spending a while away from Cam, and just says, "Sure. Languages you know by magic never get rusty?"
"Nope. But surprisingly few humans speak demon-original languages, which are in pretty common use in Hell."
"Well, if I learn those and it turns out I can also summon demons, I could summon you and glue those languages in your brain by magic forever."
"Yup! You could get me a dictionary of one of those and then we could practice until I'm fluent. But first, key."
So Cam goes to read something, occasionally muttering odd pronunciations aloud to himself, in each of the languages he knows only the long way 'round, while Sadde does key experiments.
Cam was not expecting that and winds up on the floor. "Whoa, are you okay? What happened?" Pat pat.
Whimper. Cling.
Pet pet pet. Wingwrapping. Sitting up to a less awkward snuggle position. "So - doors are one-way, looks like."
Hug, hug, hug. "It's okay. Never's a long time. You would have found me eventually."