User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-4430596-20130120030949

I'm bored, so its time for a ridiculous theory:

The remaning 5, and Nico travel to Epirus, defeat Gaea's forces, find the Doors of Death and meet up with Percy and Annabeth. Someone has to stay behind and Annabeth volunteers as she has no special powers to contribute to the group. Frank does his duty and seals the Doors, with Annabeth in Tartarus (End of book 4). We all have kinda figured that Rick's not gonna kill Annabeth or Percy, so Here's where it gets nuts. Annabeth is stuck in Tartarus with monsters closing in. So, she prays to Athena for help. Athena, no longer a crazed scynzophrenic, uses her war godess powers to lead an army down to Tartarus and save her daughter. The ensuing battle is enough to arouse the Protengoi Tartarus. Athena convinces him that his sons, the giants will destroy him, because thats just what happens in mythology. Tartarus is persuaded and agrees to help fight the giants and newly awakened Gaea (Stuff is happening in the mortal world too). This gives the Heroes of Olympus the push towards victory, and they win the 2nd Giantomachy. By the way, Annabeth was rescued by Athena.

Did I not say it was a ridiculous theroy?