From the Game's Introduction:
Beltaine is a game about the Faeries and creatures of Celtic myth living in the modern world. It's being put together quickly as a part of the 24 hour RPG project, and will hopefully serve as a springboard for a cyberpunk-and-Fae game I hope to write later.
The faerie courts are dangerous places, socially and physically, and it is easy to fall from favor. The safest thing to do when one does so is to go into exile on Earth. Some, like the Fomorians, live in permanent exile on Earth, either in hiding or disguised as humans. Fae on Earth often interbreed with humans, and their half-faerie children typically remain behind.