User blog comment:Misakichii/Which Demigod will lead the 7 to the Doors of Death?/@comment-3146930-20111026000744/@comment-91.156.23.9-20111026201617

The guide to the doors of death (if they really are an actual set of doors) could be Annabeth or maybe Nico (if he isn't being held prisoner near the location of the doors and will be freed early). As for the "certain type of demigod" thing, he/she/ ( it?) could be a totally new character who is going to be introduced later on in the series. I mean, with PJATO we had some key characters that were introduced very late to the series.