User blog comment:SayuriDarling/The Mark of Athena Official Discussion/@comment-50.55.151.60-20121028040202/@comment-3146930-20130311200430

You can't be half Roman or half Greek. The Lost Hero had 2 Greeks and 1 Roman, The Son of Neptune had 1 Greek and 2 Romans, The Mark of Athena had 4 Greeks and 0 Romans, so The House of Hades will most likely have 0 Greeks and 3 Romans (it could have 1 Greek if Annabeth is narrating).