The Fairy Queen's Realm is located in the former Demon Prison. The Demons and the fairy folk swapped dwellings after the battle of Zzyzx, the former Fairy Realm becoming the new Demon Prison, and the former Demon Prison becoming the new Fairy Realm. Many of the light creatures live in the Fairy Realm, for example unicorns and some trusted Fairies.
All of the Fairy folk at the Fairy Queen's Realm is doing their best to make it hospitable. The realm is huge, stretching many kilometers to every direction. Even though this is a world of purity, a few demons that never left Zzyzx in the battle are still hiding in sludgepits and such.