The Lost Heroine (Heroes of Olympus/Kane Chronicles crossover) [2016]
25 parts Complete Annabeth Chase wakes up in an unfamiliar house, surrounded by people in white bathrobes and weird necklaces. At the same time, Sadie Kane opens her eyes to find herself in a small, gray and silver house full of books, with a dark haired, sea-green eyed boy staring down at her. Neither of them can remember much more than their own name. The demigods of Camp Half Blood and the magicians of the Twenty-First Nome must help Annabeth and Sadie recover their memories and return home. But there is a reason they were switched, and an enemy rising to power is seeking to destroy them all. If the three ancient worlds cannot unite, more than just memories are at stake.
This takes place the summer after Blood of Olympus and Serpent's Shadow. Warning! Contains Heroes of Olympus and Kane Chronicles spoilers. The events in this book match those in the Kane Chronicles and Heroes of Olympus series, not any events from Trials of Apollo. I don't own any characters. All rights go to Rick Riordan.
Written in 2016 (age 12)