Oh, and I realize I forgot to further develop why Feyless can turn into demons from ambient magic. The ancient Feyless Humans who mated with Feyfolk did not initially turn into demons because ambient magic in the air was less prevalent back then. But as the hybrid bloodlines spread and the amount of magic users in the world grew, the ambient magic in the air became incredibly potent, eventually leading to Feyless Humans beginning to turn into demons. This is what caused Feyfolk and Feyborn to begin segregating their communities from the Feyless. And that's why they are required to wear glamour charms whenever they travel through Feyless communities. The glamour charms are like amulets or other items worn on a person that creates an illusion around them, allowing them to have various appearances. The glamour charms are also enchanted to dampen any ambient magic that the wearer might emit, thus minimizing the chance of affecting nearby Feyless.