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—
She sticks a finger inside it and a tiny hole appears on it and it starts leaking venom into the syringe. After she's done she closes up the hole and goes apply the venom to her basement-dweller self.
It is lying on the closet floor making vague noises and twitching purposelessly.
"This is really creepy," she says, and sticks the syringe into its jugular. She fills it with venom a couple more times just to be sure.
Presently she returns. "Should take a few hours, I suppose, if it works."
"I don't, we can wait more than I'd expect it to take, like, say, twelve hours, and then try attaching them to me again."
"...And you'd like to fill those twelve hours with further sex marathon, I assume."
"Exactly how much sex do you need to have before you can spend more than a couple hours at a time thinking about anything else, I'm honestly curious."
"...that's not really how my brain works. I can't generalise from my own experience to other vampires, but given the number of thoughts I can have going on at the same time, and given that I'm mated to you, I don't know if there'll be a single second for the rest of eternity I won't spend thinking about having sex with you at least a little. That said, it's not nearly as much of an insistent priority as it was when we met."
"I mean, I'm not spending my average day doing anything especially productive and sex is certainly a pleasant pastime but I do like variety."
She cocks her head a bit. "How do you feel about not doing anything especially productive all day?" she asks.
Shrug. "I take a lot of summons in the hope that one day I will get to terraform Mars, and in between lament the fact that I peaked at, how old was I, nineteen?"
"My greatest accomplishment was a century and a half ago and I have no opportunity to top it, it's frustrating. I mean, it was a pretty damn great accomplishment, but still."
"Yeah I'm starting to get why my magic thought I'd like you, what was the accomplishment?"
"...I just had this sudden very strong urge to kiss you. Of course you're awesome."
"Thank you. But this was a hundred fifty years ago and I wasn't quite anonymous enough and some asshole shot me in the head, so."