From ‘Thoughts on the Primals – Malignant Divinity’ by Archon Niniri Niri
Leviathan is a terrifying entity, worshipped by the sahagin of the Indigo Deep. Said to dwell in the depths of the ocean and often regarded as the originator of all waves in the ocean by not just the sahagin but also the sailors of other spoken races, creating a number of traditions involving the sacrifice of men to the creature. Leviathan has long been called on by the sahagin, but rarely have they called upon him to the degree that they did when the Seventh Umbral Calamity destroyed their spawning grounds, wreaking havoc upon their reproductive cycle.
The spoken tradition of the sahagin holds that before Leviathan descended upon it the world was a parched wasteland, entirely devoid of moisture, and the inhabitants of the world were dangerously in need of quenching their thirst. The gods took mercy on their subjects, calling upon Leviathan to flood the world with water drawn from his own life essence. He did so, striving long and hard to bring forth the seas, rivers and lakes and at the end of this effort he was fatally drained. The creatures of the world saw their savior dying and began to sacrifice their own lives to him in turn, rejuvenating her. Immersed in grief and admiration for those that sacrificed themselves to save him, Leviathan chose to gift his blessing to those who remained, granting a number of fish the gift of limbs, naming them sahagin and using his command of the tides to create spawning grounds for them to lay their eggs in, then disappearing into the depths of the ocean. The sahagin have worshipped him ever since. This tale is likely not to be taken literally, but may concern a historical figure or creature that ended an intense drought, or the first sahagin to seize significant spawning grounds on land for their species.
The Lord of the Whorl’s Abilities – Predictably, Leviathan’s abilities revolved primarily around the manipulation of water aether, including conjuring ‘gyre spumes’ named for great gusts of twisting water. He was also capable of drawing grant veils of water around himself by emptying the surrounding air of water, both deflecting blows and aether, which bounces upon those who test it with spellcraft.
Real World Basis – Leviathan has, in more modern years, come to refer to any astoundingly large creature or object, a criteria that the Leviathan of Eorzea certainly fits. More relevantly, however, Leviathan is likely named after the beast found in many Abrahamic faiths that takes the form of an enormous, violent sea creature associated with the end times. This fits with the Eorzean primal, as a colossal, primordial sea serpent.