this is a spoiler free article. just read the blood of Olympias, and for you people who want Percy to be the hero and not some one else don't read the book.i mean it is good but they replace Percy's view of things with Nico's view and Annebeth's view with Reyna's view.in other words Percy and Annebeth are just more characters and are no longer the heroes or even the main characters.
p.s. they give this away at the beginning of the book by as i said previously replacing Percy and Annebeth with Nico and Reyna.