"A changeling is a Faerie child that's born in the Fae Court and someone, somewhere, makes a deal to do a switch," he explained patiently. "A Fae or one of their agents---" Said because he, of course, had participated in a few switches over his years--- "takes a human baby from their crib or from the hospital and replaces it with a Fae baby. This could be for a lot of reasons... it helps them vary their bloodlines, keeps them from inbreeding... or it could be a political thing, they're trying to do something to get back at someone... many reasons. In any case, the Fae child grows up in human society, raised by parents who have no idea that this isn't the child they give birth to. As the child gets older though, they're... they're clever, they're beautiful, and they're maybe just a little bit too fast, too agile, too good at things they should struggle with. Most of them have desires to play tricks, to lie, to steal... they're good at running cons on people or convincing others to do their will from time to time."
He smiled faintly. "What happened to Faelan is... something that shouldn't have. He grew up changeling and one of the Fae, a brother I believe, pulled him back to the Courts for a 'visit'. But Fae don't take kindly to changelings... they dislike humans on a general racial level, and changelings have been tainted their whole life."