2016’s I Am Princess X is a standalone young-adult thriller by Cherie Priest. It features illustrations by Kali Ciesemier.
Once upon a time there were two schoolgirls, artist Libby and writer May. Together, they created a shared fantasy world, ruled over by Princess X. Their partnership came to an abrupt, violent end when the car containing Libby and her mother went through a bridge guard rail and into the waters below.
May did her best to convince herself that Libby somehow survived. By the time May was sixteen, she had to accept what everyone around her believed to be true: Libby was dead.
Then the stickers start appearing in Seattle windows.