Bitterblue (The Seven Kingdoms #3)
“Book 3, tentatively titled Bitterblue and currently in progress, is a companion book to both Graceling and Fire and takes place in the seven kingdoms eight years after Graceling. Bitterblue will tie all three books together in some way.
Bitterblue is the sixteen-year-old protagonist, and Katsa, Po, Giddon, Helda, and other characters from Graceling will be part of the fabric of the book. Plenty of fighting still to come!” (Goodreads)