User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-174.124.195.63-20130126030001/@comment-174.124.195.63-20130126230507

here is what is says

***SPOILER ALERT****  At the end of  Mark of Athena, Nico senses that Percy and Annabeth are still alive, despite the incredible danger they are in. Nico is right. They are alive. You WILL find out what is happening to them in the next book. They don't disappear from the story. **** END SPOILER ALERT*****