The Royal Court of the Overworld is headed by Queen Sylvanus. Some say she was once a faerie, others claim she's an elf, others still say she's actually a Dream Construct who's managed to take over. Whatever she is, she isn't owning up to it. She is a powerful and beautiful woman known as much for her benevolence as for her mercurial temperment. She lives in the Crystal Tower, the center of the Overworld.
Her children are named Dawn and Dusk and have their own tales to tell. Dawn has been a loyal son and is always found at his mother's side. However, Dusk apparently came in contact with Blight at some point and has since been corrupted. She ran away some time ago and has lived in the Underworld ever since.
Other members of the Court vary. Some are Mythos who have remained within the Overworld, others are Dream Constructs and Lucid Dreamers who have maneuvered through the ranks and won the Queen's favor and been granted noble titles by her.
In the Underworld, the Royal Court is quite different. It is headed by Emperor Sistri, a Mythos demon of firey power who has managed to keep a cohesive hold on the Underworld for several centuries now. He is extremely paranoid and so the Court tends to undergo cleansings all too often. (These cleansings usually involve removing anyone Sistri feels may be plotting against him, regardless of truth or proof.)
The Underworld Royal Court is more like a boardroom and is far more modernized. There are no lords and ladies, merely C.E.O.s and company heads. Sistri maintains the Corporate Headquarters building in the center of the Underworld. A gleaming skyscraper with dark swirling clouds surrounding it and tall, mirroresque windows.
Sistri has no children that anyone knows of. Dusk is his favorite plaything right now and he has officially adopted her as his daughter. (Though who knows how long this fancy will last.)
(This is pending animarelic's approval.)