User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-68.185.66.252-20130609025641/@comment-5774152-20130609032653

I do get Coach Hedge staying behind. I think it makes perfect sense, good job. Although, my theory is different. I think it will be Frank, Percy, or Annabeth. I am going with Frank, although that does seem kinda obivous, but there is this little thought in the back of my mind that it could be Percy or Annabeth. Hopefully I am wrong, but it is a possibility.

In the synopsis above for The House of Hades, it makes it sound like it will be either Percy or Annabeth but....i'm not sure.