...And Al-Esh said, "Though we have overthrown the Wicked Elves, we fear they will afflict us with Oblivion, for ever did they traffic with the Daedra Lords, to our sorrow and misery. Mighty are we in arms, but the Greater Demons are beyond our strength."
But the Divine Voice spake further, saying, "This will I do for the mortals of Nirn. As thou art Dragonborn, so must be thy heirs. So long as they keep the Dragonfires ever lit, so long must the Demon Lords keep to their places."
Al-Esh was grateful, yet still troubled. "How, then, if my line should fail? How will we defend ourselves?"
And there was a trembling in the world, but the Divine Voice was mild, saying, "Thy people will find a way. For unlike the Daedra, ye mortals have the creative spark, and may make new things that were not before. Where there is one defense, there may also be...."