This being was worshiped by the ancient civilizations that existed prior to the humanocentric city of Fairhaven.
Several cults, in particular that of the Greb goblins of Fairhaven, have existed over the centuries and paid abeyance and worship to this being, which is, itself, attended by beings of the lower planes. Most prefer this great primeval evil lies dormant (Cthulu-esque in stature), but there are those, for there own reasons, desire the beast to be awakened.
The awakening of the beast would likely mean destruction of the city itself, to say the least.
The Praetor Syndicate seeks the wakening of the beast, but seek to control it first before it is wakened.
The Praetor Syndicate is a deadly consortium of assassins seeking political power in Fairhaven. The Secret Keepers are loosely allied with them, though they would prefer to keep the dark being dormant. Their second choice would be to have it active, but under control.
There's more. This is just the first batch.