|Keeper of the Yellow Sign|
Source: The Thrushmoor Terror, pg(s). 88
A keeper of the Yellow Sign can usually pass for a human, but some telltale marks like a swollen face and a pale, unhealthy exterior are easily noticeable by careful observers. In natural sunlight, keepers of the Yellow Sign are weak and sluggish, like a vagrant, but at night, they become strong, attentive, and their eyes glow bright yellow. They are surrounded by an aura of gloom and abhorrence.
Keepers of the Yellow Sign hunt down unbelievers who have seen the Yellow Sign, or worse, possess an item which bears the symbol, like The King in Yellow itself, creating a sense of awareness for their impending doom among victims. They do these acts mostly out of sheer desire to inflict pain and misery, but sometimes work on behalf of a cleric of Hastur. They also have a morbid attraction to art, preferably weird, decadent creations.
Contact with a keeper of the Yellow Sign can cause living cultists of Hastur to undergo a transformation into keepers themselves. Keepers do not actively seek out new converts, and singularly focus their efforts on hunting down those unbelievers who know too much about Hastur.
Keepers of the Yellow Sign can drain enemies' energy, but doing so can cause the drained life essence to overwhelm and destroy the keeper, so they reserve this ability for when facing powerful foes or when they have the urge to consume an artist's energy (they need no conventional sustenance). Usually, a keeper of the Yellow Sign immediately regains its composure after draining energy, but sometimes they are enraptured by it and only stop when the victim dies.
Keepers of the Yellow Sign can be found where there are or used to be cults of Hastur, especially those marked by the Yellow Sign. They rarely move away from where they arose or associate with other followers of Hastur, except when they once knew each other in life (and might have transformed themselves into keepers at the same time). Even then, these keepers of the Yellow Sign prefer to be alone with their despair and insanity, only cooperating against powerful foes.
Keepers of the Yellow Sign often pose as beggars and mendicants in communities, and spend hours muttering to themselves on stoops, benches, or in gutters as they watch for evidence that passers-by could have found the Yellow Sign. They flee when offered charity, unwilling to risk giving away their true nature, and as a result are sometimes considered to be simply insane. Other times, they take on macabre jobs like gravedigger and graveyard watchman, and observe targets from cemeteries. As they exist on the fringes of society, most residents of their communities never notice that the keepers of the Yellow Sign never age or die, allowing them to remain unnoticed for centuries in the same settlement. Some keepers have remembered millennia of existence, but are usually too insane and unwilling to share their memories to anyone except the most powerful of Hastur's followers.
Original source: Robert W. Chambers, "The Yellow Sign", 1895