Religious event
It is said to be the birth of the first king of the first God.
It is said that Forever was born after the cedar cup was found, when the creatures of the Shade were slain the last champion both flayed and Gelded himself in exuberant glee. This pain and blood invoked the Grail, the Grail then birthed as it's nature, Forever. This lie has been propagated for millennia. The Grail is not thought to even exist and no God could trespass the mundane world so early. Though considered heresy by so many Forever always Endures. As this is not believed it will be eternally dismissed.