From chapter 2 of Fimbulwinter.

It could be said that the use of apocalyptic dragons as fantasy antagonists has been done an awful lot. This is absolutely true, but I like to think that this is because it's a solid trope. After all, once a fellow has tired of dragons trying to devour the world then he's clearly tired of life. So, despite it not being the most original thing in the world I'm confident that an entertaining narrative can be built around this insatiable force of nature, shamelessly stolen from Norse mythology, especially when it's resisted by some plucky fantasy Romans and their furry, and scaly, friends.