The fey lords and ladies... have always struck me as purely Arthurian and feudal, at least in outward form. There are Queens like Titania, and Kings like Oberon. If you don’t want to wind up with frog legs and a croaking voice, you better show them some respect. The fey nobles are cruel and violent and not to be trifled with. You, Dear Adventurers, are Not Worthy of their Notice....
This is all a long-winded way of saying, the Fey of Wrath of the River King are all arrogant bastards who are certain that humans, dwarves, dragonborn, and halflings are really just talking animals with less fur or more scales. This adventure is about wandering around in that alien world, with different laws and customs, and trying not to offend the Really Big Powers that run the place.