Insula De Virsta: Diadem Tribe History
Very little is known about the Diadem tribe.

They have much influence over the island, often through their own scheming.

They are the only tribe to live on Estrella Island, the tiny island that is central in the middle of the lake. It is possible that they share the island with ghosts (which technically aren't a tribe). It is a huge taboo to set foot on the island (with the exception of the limnatide, the lake spirit) unless there is a tribal council.

They are in fact fallen gods, tucked away on the island for their own safekeeping, and as a form of punishment. Their crimes often have something to do with their punishment.

Rapithwin (Oporo and Saturna) in particular has the ability to banish people from the island so that they cannot find it again. A part of her punishment that she took upon herself was to safeguard the island. The part that was imparted on her was that she is separated into three bodies and can never rejoin herself to feel whole again. Maeve's punishment is to never see her own reflection again as a result of her narcissism.

Availability: There's room for more Diadem, but not a whole lot more.