Alpha and Omega of the Opus
Book 0 asks what Story is and places the human inside it. Book XIII returns to Story after the whole journey: the awakened Son consciously participates in its telling. The arc is from being inside the Story → to participating truthfully in the creation of Story. The Exiled Prince becomes King; the King becomes Bard; the Bard remembers all the paths and sings them so they will not be forgotten.