The Pallium is an ancient watchdog organization which has charged itself with observing the supernatural elements of the world. They employ some of the finest, most powerful minds in the world, from psychics to seers and diviners and even psionics. Through these powerful minds they monitor the mystical energies of the Wash, as well as all other supernatural anomalies which occur on Earth or within the Wash.

Pallium operatives are inoculated with a serum which is primarily composed of angel's blood. The blood is not acquired through nefarious means, but is actually an item of trade between the Pallium and the angels inhabiting Earth. Once inoculated, operatives are impervious to physical death except through heart puncture. Their bodies are not invulnerable, however. They can still experience pain as a regular person might, but they cannot die unless they are decapitated. They cannot be poisoned and are also impervious to disease.