Board Thread:Spoilers!/@comment-1894786-20151104191856/@comment-4453062-20151105134329

Eskaver wrote: Once does Fairytales, myths, legends, nursery rhymes, and other forms of famous literature. People need to get it in their heads.

They will do the Underworld because it fits within those parameters. Not to mention we've had Greek mythology on this show before. King Midas, Medusa, Pegasus (in the form of the Pegasus Sail), Pandora's Box, the Fury (who they flat out say is from the Underworld), Charon, and now the fire of Prometheus in this Sunday's episode.