"In the Old Calendar Era, the astral god Ifrit betrayed the rest of his kind and caused the downfall of the nation of Solheim. Ifrit began the Great War of Old that killed millions. Growing jealous of humanity's successes without relying on the gods, Ifrit sent forth the Starscourge, photosynthetic organisms that parasitize people and transform them into monsters."
"Ifrit became known as the Betrayer, and is opposed by the other astrals who want to purge the darkness Ifrit brings forth. The darkness of the Starscourge is countered by the powers of light. Bahamut, who appears to be the leader of the astrals, gifted a Crystal to mankind. It exudes great magical power, and is said to hold the soul of the world. Bahamut handpicked two people who would become able to wield divine powers to counteract the Starscourge, and to one day save the world from it. This became the prophecy of the True King: In a time unknown, only a prophecy keeps hope alive in people's hearts. "When darkness veils the world, the King of Light shall come."
"Two thousand years ago, Ardyn Lucis Caelum was a Lucian king chosen by the astrals to save Eos from the Starscourge. Ardyn absorbed countless daemons to saved thousands across the world, yet was denounced by the astrals as unclean. He was denied entry to the Astral Realm and demonized by a jealous future king who later became chosen by the Crystal. As his transition rendered him immortal, Ardyn became the embodiment of daemonic influence in the world and the Starscourge. He took the surname of "Izunia" and vowed to one day have his revenge on the True King's descendants and the Crystal. "
"Ardyn bided his time for millennia before establishing himself as chancellor to Iedolas Aldercapt, the Emperor of Niflheim. He provided his knowledge to begin his plan for revenge. With Ardyn's coaxing the Empire began to use daemons for experiments for creating a magitek infantry, and to deploy as weapons of war. A mysterious "vanishing disease" began to ravage the imperial lands. Although the Starscourge is not a new phenomenon, it was poorly understood, and for a time the vanishing phenomenon that has people disappear into thin air was not understood to be a disease. In truth, the people who become afflicted with Starscourge disappear when they turn into daemons. "
"Overpowered by Noctis, Ardyn is finally able to rest in peace. His body fades away, and his spirit is destroyed when Noctis—who gave his life to halt the Starscourge and purge the daemons—uses the power of those he cherishes and the Lucian kings of old to land a final blow. As Ardyn's soul is erased, the darkness is lifted, daemons disappear and the sun rises. The prophecy fulfilled, the Ring of the Lucii disintegrates as the Lucian bloodline ends with Noctis's death. "