User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-8848260-20131003231046

Rick did an interview about HoH where he talks about some of the characters that will be returning to the series to do cameos and some information on what's going to happen in book 5. http://www.publishersweekly.com/pw/by-topic/childrens/childrens-authors/article/59361-the-house-of-riordan-an-update.html

also, rick released the deleted scene from tlo with percy seeing nancy for the first time in years: http://rickriordan.blogspot.ca/2013/10/a-deleted-scene-from-last-olympian.html