Castiel is the spirit of a forest, and Dean is the guy who comes to the forest to relax. Which would be fine, except now he wants to cut down a tree to make room for a cabin, and Castiel will do whatever he has to in order to save the old sycamore tree from injury at the hands of a frustratingly attractive human.
He didn't know what he expected. Maybe piles and piles of gold and treasure, closely guarded by a massive scaly beast, red or blue or black and breathing fire. Maybe with wings, maybe not. Maybe it would have red eyes and maybe it would attack as soon as it saw Dean. He was expecting—well, he was expecting a dragon. Not... this. "This" being a young man with dark hair, too blue eyes, and a tilt to his head. He didn't... look like a dragon. He just looked confused. (Dean/Castiel fairy tale AU in which Dean is a prince who goes to slay a dragon, and Castiel is cursed to turn into a dragon every night.)