Bill hums, "Gotta say, it makes one a bad deal-maker if one doesn't compromise..." he muses, "But you know what you want, I can respect that,"
The demon politely pushes Rick's hand off, dropping the teasing and happier mask. Voice taking on a more serious tone, "Like I said, even with your science, I can't just snap my fingers and give you my power, or snap the knowledge of it into your head. Like...I literally can't. Magic takes on different forms; there isn't one right or wrong way. Maybe in your section of the multiverse's magic can be contained like that, but that's not how mine works,"
He hums, pacing back and forth in the air, "Maybe...yes...okay, maybe...hmmm...." he's actually thinking aloud this time, "Okay! Your science can't contain my magic, but my magic can contain my magic!"
He snaps his fingers and summons a magic spell; hundreds and hundreds of pages of knowledge, spells, and rituals fold and morph together into one thick grimore. It snaps shut, and Bill uses one finger to lift it up for Rick to see.
"Here you go, kid! All of my magical knowledge in one book! Nothing left out, nothing I can hide. All of my power, in a physical thing you can use to teach yourself. If I learn something new, this book will automatically update itself. If it fails to do so, or I try to hide something, our deal will break,"
Before Rick can take the book, however, it's Bill's turn to wag a finger, "Ah ah. I have a few questions about my side of the deal," he says. He floats close to Rick again, "Are you offering your mind to me? Or are you trying to pawn me off to a clone?"