The Dragon He Used to Be

A thousand years before the epic, the ancient Iranian hymns know him as a creature with three mouths, three heads and six eyes, who sacrifices in Babylon and asks to empty the whole earth of men — and is refused, every time, in three separate hymns, while the hero asking to overcome him is granted it each time. That patterning is the point those hymns make. And in them the hero does not bind him. He kills him. The chaining, the mountain and the monster who waits out the ages are later, and even in the books that added them the ending will not settle: he is killed by a different hero, or is not killed at all but converted.