Ragnarök

In the Prime Universe, Ragnarök was the set of prophesied events which would see the end of the reign of the Aesir gods. It would be sparked by Loki and his son Fenrir being freed from their respective imprisonments, and see the death of Odin at the hands of Fenrir himself.

As the power of the old gods and their magic waned, Ragnarök became less of a certainty, and it became possible for Fenrir and Loki to escape their bonds in ways others than those that had been foretold. However, Fenrir insisted that they not deviate from the prophecy, because he believed that contradicting the predictions would weaken their overall power even further. (PROSE: The Winter Quests)