Lord Of Cinder's History
Before the flame existed, little of Gwyn's life is known, save that he had an uncle named Lloyd. He was surrounded by knights when he found the flame, and was dressed in his regalia, so it is possible that he may have been a king long before that moment.
At the dawn of the Age of Fire, Gwyn discovered a Lord Soul along with the Furtive Pygmy, Gravelord Nito, and the Witch of Izalith. His soul allowed him to manipulate light, and generate a substance called lightning. They allied with Seath the Scaleless and amassed an army, and with their power, challenged the Everlasting Dragons for dominion of the World. His mighty bolts peeled apart their ancient scales, allowing them to be killed by other attacks, and they were ultimately defeated, but not eliminated.
And thus the Age of Fire began, with Gwyn becoming the king of Lordran. He lived with his clan, who became a new and varied race known as Gods, in their city of Anor Londo. They often hunted the descendants of the dragons for sport, for which many of their powers were developed. This did not include Seath, for he received recognition for his deeds, and was made a part of the nobility.
When the flames began to fade, Gwyn and the other Lords did all they could to find a solution. The Witch of Izalith attempted to recreate the First Flame from her own Lord's Soul, but the attempt went horribly awry, mutating the Witch into the terrible Bed of Chaos, which spewed forth malformed demons whom Gwyn's faithful Silver Knights fought, but the flames of the demons charred their armor black, thus becoming Black Knights. Seeing no other choice, Gwyn left Anor Londo and traveled to the Kiln of the First Flame, to link the First Flame, thus prolonging the Age of Fire. When he left, he divided his own soul among his clan and his children, and granted parts to both the Four Kings and Seath, along with others.
In linking the flame, Gwyn sacrificed himself; with his powerful soul providing fuel for the flames, prolonging the Age of Fire. A great many of his Black Knights followed him into the Kiln and were reduced to ash when he linked the fire, wandering Lordran as disembodied spirits for eternity. His Lord Soul was able to keep the fire burning for centuries, but it left Gwyn to Hollow.
It is implied that at least one thousand years have passed when the events of Dark Souls begin. Gwynevere, Princess of Sunlight, Kingseeker Frampt and Darkstalker Kaathe give the Chosen Undead alternating viewpoints of Gwyn. Gwynevere claims that it is the Chosen Undead's duty to succeed Gwyn, stating that their success would "avert further Undead sacrifices" and that without Fire, "all shall be a frigid and frightful Dark" �?? a perspective that Frampt shares. As this Gwynevere is actually an illusion, whether or not they are being entirely truthful is left unresolved.
On the other hand, Kaathe asserts that the Age of Dark �?? the apparent "age of men" �?? would naturally follow the Age of Fire, but Gwyn, in dire fear of both the Dark and humans, resisted the course of nature by sacrificing himself to link the Fire. Unlike Frampt, Kaathe believes it is the Chosen Undead's fate to "destroy the fading Lord Gwyn, [...] become the Fourth Lord, [and] usher in an Age of Dark".
