User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-4547258-20130209235241

So I think I have a theory about the third prophecy line, aka the one no one knows the heck about. What if that line refers to when Percy made Nico promise he'd safely help the other five journey to the House of Hades in Greece? But I really really really hope that my theory isn't true, or Nico is going to die ;-;