Listen: the Three-Faced God created the Chain of Creation out of the chaos of Perimal Darkling, yes? […] The Merikit say that this world rests on the back of a great chaos serpent, left over from the beginning. Its mouth is the great maelstrom called the Maw, that drinks the Eastern Sea. Its offspring run like veins under the earth and water. Some call weirding the Serpent's breath. When it passes over the land, the Serpent's brood awakes, and that includes the River Snake, which lies under the Silver.
– Cattila, Seeker's Mask, "Part IV: Restormir", VI
The Chaos Serpent is, in the Merikit religious tradition, the great primal snake said to lie under Rathillien. Its mouth is the great whirlpool maelstrom known as the Chaos Maw in the Eastern Sea Its children are known as the Serpent's Brood, which includes the River Snake. Wierding is sometimes called the "Serpent's Breath", and the Merikit say it wakes the Serpent's Brood, including the River Snake, causing earthquakes. Disturbing the River Snake can in turn wake the Chaos Serpent, which is something the Merikit fear.
Cattila speaks of the Chaos Serpent being linked to the chaos of Perimal Darkling, in Kencyr religion.
↑Seeker's Mask, "Characters Past and Present" — "Chaos Serpent: the great, primal snake said to lie under Rathillien, whose mouth is the maelstrom known as the Maw"
↑Seeker's Mask, "Part VIII: Kithorn" — " 'All four of us, here in the north, treading on the River Snake's back… woke him up, didn't we? […] Now his hunger rouses all the Brood, who may wake the Chaos Serpent itself and so end all.' "
↑Seeker's Mask, "Part VIII: Kithorn" — "Cattila claimed that the Chaos Serpent and its brood were a primordial part of Perimal Darkling, […] what a mess they all were in, Kencyr and Rathillien alike, if there truly was a link between Gerridon and the Chaos Serpent."