Becoming human without permission was the original sin that the people of Fontaine had borne since their birth.
Since the people of Fontaine were merely "incomplete humans" transformed from Oceanids, touching Primordial Sea Water would cause the primordial energy within their bodies to yearn uncontrollably to return to the sea. In the game, this manifested as their bodies dissolving directly into water.
This prophecy was the punishment Celestia had imposed on the people of Fontaine. One day, the ocean, mixed with Primordial Sea Water, would rise and submerge all of Fontaine.
When that day came, all the people of Fontaine would dissolve in the ocean, turn back into Oceanids, and return to the Primordial Sea. Only then would their sin of becoming human without permission be washed away.
In the game, the appearance of the All-Devouring Narwhal triggered an enormous disaster, causing the sea level to rise and fulfilling the prophecy.
Noelle had once asked Ellin whether Fontaine's disaster would never happen if the All-Devouring Narwhal could not follow them into this universe.
Ellin's answer was, "Unlikely."
Yes, the so-called prophecy was actually future history-something that was certain to happen.
You could think of it as a script the Heavenly Principles had written in advance to punish Fontaine and the Hydro Archon.
The sea level would rise, and seawater mixed with Primordial Sea Water would submerge Fontaine. This was history that was certain to happen, a plot already written into Celestia's script.
So even without the All-Devouring Narwhal, something like a Sun-Swallowing Shark or a Moon-Devouring Fish, or some other cause, would make Primordial Sea Water erupt. The sea level would rise, fulfilling the prophecy.
Five hundred years ago, Egeria died. From among her many Oceanid familiars, she chose Focalors to become the next Hydro Archon.
The moment Focalors