WORK IN PROGRESS - all info in accurate but perhaps poorly written atm
Similarly to Fey, Hellas is a Realm unique in that it has always been separate from the lands beyond, though it was not always so. In the time when the Gods still walked amongst the peoples, the Demons ran rampant across the lands, spreading terror and bloodshed in their path, much to the delight of their creator. But the rest of the Gods would not suffer this obstruction to their 'utopia' and ordered the Demons to be unmade by their creator in order to protect the rest of the peoples from their violence. Their creator refused however, his love for his children too great to be cowed by the demands of his deific siblings. Instead of destroying the demons, he severed a piece of the land from the earth, reforging it into a home outside of reality where the demons could live according to their true nature. This land was what would come to be known as Hellas, a land separate and sealed from the Realms beyond, exit from which can only be gained by the opening of a gate from the outside.
Survival within Hellas is nearly impossible for any living thing outside of the Demons themselves, and even then, only just. Active volcanoes, lifeless wastes, fields of toxic gases, and roving packs of the more feral kinds of Demons are only some of the dangers to be found lurking around every proverbial corner. Amongst this are scattered the numerous Domains; areas of influence created by Greater Demons, usually members of the Fiendish Court, within which the terrain and and even the laws of reality are shaped according to the master's essence.