Whilst the twins had much in common, they were also very different.
The older twin strove to place order in the universe so that it may protect the Fay. The younger twin revealed in the chaos of the universe and life that could be found in it.
To the younger twin, the Fay empire was simply part of that chaos. Something that would grow and then die as part of the never-ending cycle. To the older, the purpose of the universe was to serve the Fay. Without the Fay, there was no point of the universe.
Together the twins explored the universe for knowledge and power that they could grow the Empire. Their search came to an end when they stood on the deck of their ship, looking into the well of souls. The source of all life from which the souls of every living creature originates and the place it returns to on death.
The elder twin saw at once a way to create races of creatures without souls. Slave races that would never be truly alive and far easier to control that the wild anarchy of life. This unlimited, never stopping work force would allow the Fay empire to dominate the entire multi-verse.
The younger twin objected, claiming no one has the right to deny another their soul but the elder twin ignore him. He created the slave races. Armies of soulless, eternal, obedient creatures that are neither living nor dead.
Appalled, the younger twin abandoned his brother and the Fay empire. Sailing across dimensions, the younger twin took a ship far from his people, beyond the limits of even the Fay's vast knowledge. What he hoped to find, no one knew but the search took millennium and in the Empire, the younger twin was all but forgotten.