The Progenitor Myth

The Progenitor Celestials are Alder, Abdera, and Arcus. The legend of the origin of the world of Alder states that these three great celestials created the world and created the Progenitor Prophecy. The Progenitors are often described as being siblings.

Summary

According to the myth, the emptiness before creation was the domain of three mighty celestials. Golden Arcus was the source of all magic and light, gentle Alder was fountain of life and beauty, and cruel Abdera was the master of knowledge and shadow. Together, they held dominion over the fate of all, and they pondered the proper shape of the universe.
In the beginning, they worked together. They started with planes. Cambria and Sol bore the sublime touch of of Arcus, while Igni and Noir bore the trademark dominance of Abdera. Alder sought to mediate by populating all with life to show what was possible with their unique creations, but could not bridge the divide between her siblings. When the time came to create the final, central plane, the tensions between Arcus and Abdera could no longer be contained. Abdera tore into her sibling, cleaving the golden celestial in two and spattering his blood across the sky. When Alder saw what Abdera had done, she wept and ran her hands through the cosmos and grabbed a few drops of Arcus's blood. Alder, knowing that she was not powerful enough to defeat her murderous sibling, refused to fight but instead embraced Abdera. As she did, she called upon the power of magic still within those drops of Arcus's blood and bound Abdera to herself. Then she called upon the powers of life, giving birth to soil, air, and ocean and, transformed herself into a living prison that Abdera could never escape.
Thus, Alder became the world on which all life grew. To this day, she nurtures and sustains all. Arcus's remains became the twin suns and his scattered blood became the stars in the sky, save for the few that Alder holds in her hand, which became the worldrunes binding Abdera. Abdera remains trapped within - the shadow below, the mother of monsters, and the source of all darkness - forever struggling to escape and bring an end to all.

Variations & Mutation

Versions of the Progenitor myth are prevalent across all known cultures, with some variations. Some describe the progenitors as great dragons, others as gods or fiends. Some argue that there were once five Progenitors or that Abdera was betrayed by Arcus first.

In Art

"The Three" are one of the most common subjects of art throughout the ages. Archaeologists have found caves within the Shivering Isles which depict a bound Abdera struggling to free herself.