Oh, shut up and help me remodel the Blank (Mobius) page!
Blanks are essentially men with no memory, no sense of self, and no discernable purpose since they washed ashore on Palamecia. Hence, they are blank slates, guided only by the two most fluid factors in this world: its law, and the ever-mutable prophecy that has spread to all corners of the land. Of the many tales bound to Palamecia and its Blanks, only one is certain truth: those without the will to fight remain nameless, and are quickly forgotten.
Blanks are transported to Palamecia via magic conduits, the true nature of which is not explained. While traveling through the conduit, each Blank may be given the story of Palamecia courtesy Vox. Once the Blanks land, Vox provides further information about the quest for the title "Warrior of Light"; but for his assistance, Vox demands complete adherence to the prophecy and his commands, even going so far as to ask a Blank to kill any living threat to the prophecy as well as any in egregious violation of Palamecia's laws, as Garland, Meia, and the unnamed Warrior of Light candidate of the past.
Throughout the story, Wol, the player avatar, is one such Blank. As he develops and witnesses the events of the story, he begins to question and even to challenge his expected place in the world, all the while gaining some degree of acclaim as he moves closer to the legend of the Warrior of Light.
An aged, heavily-scarred man appearing wise in his ways, Cid's journey became the basis for the Warrior of Light tale. He, too, was quick to question his purpose, but fought and survived many battles during his quest. Now unable to continue, he serves as a guide for any who seek to become the Warrior of Light.