Surtr

Surtr is the oldest enemy in creation — a primordial fire-jotunn who ruled Muspelheim before Asgard raised its first hall, and who has waited at the burning edge of the Nine Realms ever since. He is less a person than a force: the embodiment of entropy and ending, fire given will and a grudge against everything that endures.

Every prophecy of Ragnarök ends with Surtr. When the seals fail and the Burning Branch opens, he will cross into the realms with a sword brighter than the sun and set all of creation alight — and from those ashes, the seers say, whatever comes next will grow. The Aesir have built their entire strategy around delaying that single inevitable march.

The Fire at the End

TODO: the burning host, the sealing of the Burning Branch, and Surtr's place in the long countdown to Ragnarök.