Perses, the Twelfth One, is a Progenitor Perennial and one of the Sacred Twelve. It is the primordial embodiment of purity, standing in opposition to Tau, the embodiment of corruption and its sole parent. As the antithesis of creation, Perses was born as the natural enemy of its brethren, and was immediately obliterated by its fellow Perennials and its remains entombed in the Graveyard. Remnants of Perses survived its destruction and entombment, allowing the survival of the concept of purity, albeit in a severely weakened and altered form.