The sole structure on the barren rock of Nathema, the Sanitarium was where Valkorion sent powerful Force users who opposed him for gruesome research experiments. The Force void enveloping the world limited the subjects' ability to resist or escape, making it the perfect laboratory and prison.
The Sanitarium is home to a mysterious sect of Force-sensitives called the Nathema Zealots, though day-to-day order is maintained by the Keepers--specially trained Abyssin who serve as guards and caretakers. The halls are also patrolled by mutated creatures from other worlds that are genetically engineered to instill fear, terror, and obedience in the Sanitarium's unwilling residents. The operation is overseen by an Anomid scientist named Jarak--an outcast among his own kind for the deviant nature of his research.
Vaylin is the only inmate to ever leave Nathema alive, though she still bears the mental scars from the horrors she endured during her incarceration.