The Fading Light was created along with The Dark Mind when the universe started in Eden-Alpha. He created everything good in the world, and then his soul resided in Am Dhaegar. However, when Dark Mind possessed Zalgo and turned him insane, Zalgo killed Am Dhaegar, which also dealt a blow to Fading Light which could not be repaired. The Dark Mind's victory did not last long though; Zalgo's children, Tae and Akriex, killed (supposedly, in reality put him in a coma) Zalgo shortly after, trapping the Dark Mind inside him for 666 years. Fading Light didn't appear himself for ages upon ages after the incident, and only left behind the feeling of hope in the hearts of the good.
Skipping to 647 years after Eden-Alpha, during Y-Delta, the Death Doctor finds about the existence Fading Light and Dark Mind, and researches into it. He attempts to find Faulkon, and set things right.
Then the Death Doctor and Faulkon find Fading Light, and learn everything they can from him. Skipping to 666 years after Eden-Alpha, during Z-Omega, Fading Light has one last final battle with Dark Mind, and is defeated. Fading Light finally fades away, leaving only 4 of his beams behind, and his sword, which are picked up by Faulkon and the Death Doctor, respectively.