User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-5774152-20121125033314/@comment-4649443-20121128041430

I know...according to Nico, Percy is the most powerful half-blood he's ever met. His blood is powerful. Annabeth is taken because without her, the others won't have a clue of what to do. Plus, I think she'll have power over the Parthenos.