Can you tell us about author Cas and boy king Sam? Just headcanons out how you think it'll end up or whatever :)
Okay, so... Sam is not technically King yet. Or, well, technically he is, but he doesn’t have any real power. Or, okay, technically he does, but he doesn’t know how to use it. That’s why he roped Crowley, a pretty low-level crossroads demon, into tutoring him. Because Sam was supposed to be just stuck on the throne as a figurehead - Hell needs a king, and everyone figured that if they put some weird half-demon brat on the throne, they could get away with whatever they wanted to. Sam was totally not okay with that, and has determined that if he learns all the boring old laws and regulations, then he can keep things in order and effectively save the human race.
Cas is a normal, perfectly human (he thinks so, anyways) author, who writes and illustrates his own book. He had no idea that the star with the random squiggles around it he had doodled would actually summon the king of Hell. He thought they were just pretty. And then suddenly, he lights his Vanilla Cupcake Yankee Candle, and there’s a very disgruntled young man in his living room who just got yanked out of bed, fluffy pajamas and all. Also yellow eyes. And grey skin. And... are those little horns protruding from his head?
(Most demons are hideous, but they can also cloak their true forms. As a half demon, Sam got off pretty let in the “horrifyingly monstrous appearance” department, but he also can’t change his appearance. Bummer.)
Cas is totally absolutely wrong about being completely human. He’s like... 0.0004617% angel. Nowhere near enough to affect him at all, just enough for him to shine like a beacon to supernatural beings. It’s why he always had so many different monsters in his room at night when he was a kid. That’s where the ideas for his books come from; they’re very popular, because the message is basically “Yeah, there’s a monster in the closet, but he’s eating all the bad dreams before they can get to you, so it’s cool.”
Sam returns to hell, anyways, but a few weeks later Cas summons him again, because he wants to make sure he’s not losing his mind. They get along splendidly, once Sam gives Cas his cell phone number, so that he can control when and where he gets to see Cas (he’s gotten in trouble one too many times for disappearing during an important meeting.)
So then Sam slowly but surely takes over Hell, which improves life on earth drastically, and Cas’s books are on the New York Times Best Sellers List for