[First posted at Slacktivist (page 9).]
[On demons growing up as human beings as described in the novel idea here.]
Mine wasn't so much that that happened regularly, in fact I was thinking of it as a novel idea that no one had ever thought of before. I think that I had a lot of obvious seeming things that I thought of as novel ideas*. And suddenly it hits me: novel ideas to be used in ideas for novels. Perhaps "novel" wasn't the right word. Previously unthought ideas.
I do think I realized at some point that it didn't make a whole lot of sense that no one in the history the universe had this plan before and tried to justify it by saying that most demons wouldn't want to be tied to a human body in the first place and were perfectly happy to be in hell torturing people. Those that weren't weren't trusted enough to get earth duty, so first the protagonist demon had to work his way up in the hierarchy somewhat which was difficult and slow because protagademon couldn't be evil to save his soul. (He'd be something like Fuchsia from Sinfest after she fell in love with Crimminy.)
So part of it was that most demons weren't coming at it from a "there must be some way out of here," angle and most of those who were didn't manage to implement any plans. First he had to get trusted enough to be given a shot at possession, then he had to convince someone more trusted to go along with this plan because he still wouldn't be trusted enough to choose an assignment, certainly not enough to choose one that would allow him to slip away unnoticed, and even then it was hard to implement (try to take possession too early and it's not a human yet, so you bounce, take it too late and there's already a soul so it's like any other possession and not at all exorcism proof, you need to get it just right) and didn't exactly work perfectly (main character's amnesia being the result of a head on collision with a human soul.)
So it really wasn't angels/demons/both are born as humans as part of the setting but more of, for the first time ever four demons used a complicated possession plot to free themselves from Hell.
* The one that comes to mind is the tree of knowledge. It's the fruit of the tree of knowledge, not the fruit of knowledge. The fruit isn't all of knowledge, just a part of it. So I decided that to get the full blown "I am enlightened," effect (which I suddenly find myself imagining said in the manner of, "I know Kung Fu" from The Matrix) you need to eat the whole tree. And what is a seed if not a whole tree?
So far this is just a minor quirk of the setting, but I remember then thinking that the response to learning that the characters from the first book figured this out and ate the seeds was something along the lines of, "How did they think of that? No one's ever thought of that. Did someone tell them? In all of human history no one ever came up with that before. How could they possibly think of that?"
And, obviously, they took some seeds with them so they could grow a new tree of knowledge in their eventual back yard. Because that's what you do.