You want it in writing.

Selas narrows her eyes at you, thoroughly annoyed now. You hold your ground, and she unzips the air in front of her. Pulling out a typewriter and a sheet of vellum, she adjusts her librarian's glasses and starts typing, angrily smacking the carriage back every time. When she's done, she tears the contract out of the typewriter, tosses it into the air and whistles. A cloud of black smoke appears in front of you, and when it clears, a small demon with comically large glasses is floating next to her. The demon reads through the contract thoroughly and nods, floating it over to you.

Being careful not to touch it, you analyze each line of every keystroke of this contract, looking for any loophole that she might have snuck in between the lines. Not seeing anything too fishy or alarming, you nod in agreement. The small demon very promptly snaps it's finger off and hands it over to Selas, who signs at the bottom and then hands it to you. You take the finger pen and tentatively sign the contract as well, preparing yourself for a family of half-demons. Rolling the contract up and swallowing it, the demon bows to the both of you and vanishes.

You brace yourself for pain or blinding light or to be immediately jumped by either Selas or her friends, but nothing happens. You look around nervously before asking her if something is supposed to happen. "Not yet," she pouts, shoving the typewriter back through the zip and closing it up. "It's an official contracted request. It needs to be properly processed, reviewed, yada, yada, yada. It's gonna take a while."

"I'm surprised you have a bureaucracy. How long do you think it'll take?"

"Where do you think humans got the idea from?" She replies, tucking her glasses into her cleavage. "In your time, about a week. Back home, he'll be lucky if he gets his number after a year in line. So what do you want to do now?"