The Fabula Nova Crystallis mythology was revealed in a video shown at Square Enix 1st Production Department Premiere event on January 18, 2011.
The universe of the Fabula Nova Crystallis series is divided in two – the Mortal World, the realm of the living, and the Unseen World, the realm of the dead. In the beginning, the god Bhunivelze had killed his mother, Mwynn, in order to take full control of the Mortal World for himself. As a result, Mwynn was sent into the Unseen World.
Bhunivelze creates Pulse.
Despite achieving his goal of total control of the Mortal World, Bhunivelze became troubled. He believed that Mwynn had placed a curse on the realm of the living so that it would one day be destroyed. In order to put a stop to the curse Bhunivelze sought to destroy his mother once and for all, but was unable to reach the Unseen World without giving up control of the Mortal World. To find the entrance to the realm of the dead, Bhunivelze created the fal'Cie Pulse, tasked with searching the world for the door to the Unseen World.
Bhunivelze creates Etro, but doesn't give her any powers.
To assist Pulse, Bhunivelze soon after created the fal'Cie Etro, but became distraught to discover that he unknowingly created her in the likeness of Mwynn. As a result, Bhunivelze gave Etro no powers. To replace Etro, Bhunivelze created the fal'Cie Lindzei, tasked with protecting the world and Bhunivelze himself. With the fal'Cie at work, Bhunivelze put himself into a deep crystal sleep, to be awoken only when the door to the Unseen World was found.
Humankind is born out of Etro's blood.
Though Pulse and Lindzei were given a task to fulfill by their creator, Etro became distressed over her lack of power and purpose in the world. Out of despair, Etro killed herself and disappeared from the Mortal World. From Etro's spilled blood, humanity took root and grew. Etro felt a bond with these creatures she unknowingly created, as they, like her, were destined to die.
In the Unseen World, Etro discovered Mwynn being consumed by a strange energy mass known as chaos. With her last breath, Mwynn tasked Etro with protecting the balance of the universe, for if the balance between the Visible and Unseen Worlds was to be disrupted, the universe itself would collapse. The death of the Mortal World was not a curse, but in fact, fate.
Mwynn told Etro she must protect the world balance.
Despite this, Etro did not understand what Mwynn had asked of her as she was consumed by the chaos. Etro became lonely, though she felt affection toward humans, who lived only to die. Etro placed a piece of chaos within each human being, which came to be known as the "heart". So long as humans continue to be born and die, then the universe will remain in balance.
Pulse continued to craft the world as he saw fit, while Lindzei protected the world and crafted the floating paradise of Cocoon for the humans. One day, Pulse and Lindzei absconded from the world, never to be seen again. Many of the humans, in turn, worshiped – and some abhorred – these fal'Cie as gods. Etro, meanwhile, became known as the Goddess of Death, who waited to greet each human as they passed through the door to the Unseen World.
And Bhunivelze continues to sleep until the end of time. -
FNC Wikia
