User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-2079715-20130302084701

Since Riordan is not known for leaving loose ends in his books, my guess is that the Great Seven will be on their own till the end of the journey. It's like their own Odyssey. The war will be fought on 2 fronts. 1st front will be Romans and Greeks united after Athena does her magic. Riordan won't allow for the finnale of HoO to be any less powerful and mindblowing than finale of PJ&O. The Great Seven will face Porphirion and his army at Mount Olympus, the 2nd front.

To storm or fire the world must fall. I still can't figure out who is storm and who is fire.

The Son of Neptune will drown ... I dunno about you but that almost drowning in the black water isn't the one mentioned in prophecy. Percy is still to face his true drowning. Also, we will see only scenes from Tartarus, meaning we will probably see Percy and Annabeth through the dream of somebody else. Riordan won't actually write any chapter of Percy or Annabeth. Instead, he will do a POV of Jason, Frank, Hazel and Nico. Nico will probably be our main source of information for Percy and Annabeth. Or Piper with her dagger.

Also, Mermen hero camp will play some role in final events. I have a hunch only though.

And for the HoH, I believe Percy and Annabeth will find some soul who is not vengeful. My wild guess is that they will find someone in Tartarus who hates Gaea more than Gods, and who will stay behind and close the Doors from the other side, so the Percy and Annabeth could escape. Too many Gods in the series has allready mentioned that victory never comes without sacrifice. There WILL be sacrifice in HoH. 100%

And I bet we all miss Grover and Chiron and Tyson. RR will probably give them some badass role as well.

Anyway, that's all I have for now.