The Athlanteen people are signatories of the Unseelie Accords. They are the descendants of the original inhabitants of the legendary island of what has become known from the time of antiquity as Atlantis.
The original name of the island nation was Athlanteena. Unlike the great legend written about by Plato, the island was not destroyed by any ancient Greek Gods; but was instead destroyed in one of the earliest known conflicts between the Old Ones, Outsiders and their allies.
In the original war, the Athlanteen people, who are descended from Fae, managed to stop a full-fledged godlike Old One,whose name has fallen from memory.
As powerful practitioners of Thaumaturgy, the Athlanteen were able to stop the invasion that threatened our world, but at great cost. The corpse of the defeated God, landed upon their city driving it beneath the waves. This destruction would later inspire the legend of Atlantis.
Those that were not destroyed outright, were inundated in a wave of Old One blood. This blood interacted with the bodies of the survivors, causing massive degenerative transformations, merging their magical nature with the twisted aspects of the Old Ones.
Among the aftermath the cursed transformation seems to follow the maternal line, creating a deficit in the production of male offspring. Males do exist but are exceedingly rare. A hunger for flesh is now endemic to the species.