User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-10750309-20130716112029/@comment-8043224-20130821054213

OR it could mean Nico,I mean in the first great prophecy everyone thought it was Percy right? So maybe To storm or fire the world must fall. is talking about Nico,'cause Hades has control over the Underworld which i'm sure has tons of fire.Though he isn't part of the seven half-bloods,his just accompanying them to the Doors of Death.