User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-4738785-20121022024745/@comment-75.134.197.218-20121027011829

I agree. You don't kill off your main characters. Nico is one of the demigods that floats through the books. He's important. The big Doors of Death battle will be book 5. HoH will probably include PoVs from Percy and/or Annabeth and Nico. The title always involves a key character. I'd like to have more elaboration on Tartarus. Also, a monster in Tartarus may be the one to allow Percy and Annabeth to escape.