The shape of Kos resembles a large blend of a fish, a mollusk, and even a human woman, all with bright white skin and blue scales. Its dimensions almost the size of a small ship, one cannot avert their eyes at this mysterious and sublime creature.
Although now a corpse, in the throes of death it births the Orphan of Kos, who will battle the Hunter in a frenzied fit of anger and confusion. The body of Kos is presumably infected by a number of kos parasites, a type of mollusk that resembles a "portuguese man o'war", seeing as the Orphan drops one upon its defeat.
The being named Kos, or sometimes referred to as Kosm, was apparently revered by the Fishing Hamlet's inhabitants, who were also mutated by her cosmic power. Some theories say that she was washed ashore after dying by unknown means, and the villagers began cultivating the parasites within her corpse, altered by their cosmic nature. Others believe she lurked off the shore and sent the villagers the innumerable squids and fish in return for their worship of her.
In their search for eyes, Willem sent scholars from Byrgenwerth to hunt the villagers and investigate the nature of their transformations, brutally cutting open skulls in order to extract their eyes. Whether or not they had a hand in the death of Kos is unknown, but most agree that the hunters did some blasphemous violation of her body, likely by dissecting her to get her eldritch blood. Only one hunter, Lady Maria, was bluntly confirmed to have been part of this excursion, which troubled her morality to the point that she forsook the weapon she used to kill with, casting the thing into a well. Others that have been theorized to play a part in that hunt include Laurence, Gehrman, Ludwig, and Willem himself perhaps.
But while the body of Kos rotted on the shore, the mind of the Great Ones is unending, and from the vantage of the cosmic planes, she laid a curse upon the hunters. Those like the ones that desecrated her and the villagers, seeking to relish blood and eyes, would be cast into the Hunter's Nightmare. Engaged in an endless hunt, it is something that no hunter can escape, and it was implied that certain individuals would fade into the Nightmare at random, implying their life deeds to be especially punishable.
It is unclear why killing the Orphan breaks the curse.
- If you look at its face, it appears unusually human-like.
- When fighting Orphan of Kos, in his second phase, he will cry out to his mother, who will aid him with yellow-ish waves of lightning that originate from her body. The Fishman Mage can also call down a yellow lightning, indicating Kos also consider the Fishing Hamlet residents her children.
- Since the existence of Kos and possibly that of its son; an abomination born totally formed and all too human-like instead of being similar in appearance to a celestial child, is referred to as "the great sin of the fathers," it is possible that this Great One was the first attempt to transform a human into a superior being.
- The ideas behind Kos seem to reference the Lovecraft story "The Shadow over Innsmouth".