Ciena Ree is a human female from the Outer Rim world Jelucan, introduced in Claudia Gray's Lost Stars (Disney–Lucasfilm Press, 2015). She and Thane Kyrell grow up together, enter the Royal Imperial Academy together, and end the book on opposite sides of the war.
The oath
Ciena comes from Jelucan's first-wave settlers and their strict tradition of honour — an oath, once given, is not a contract you can renegotiate when circumstances change. That is the entire tragedy. She serves through Alderaan, through Endor, through everything the Empire does, not because she approves of it but because she does not believe a person is permitted to walk away from a sworn duty.
Why the book works
Lost Stars is the best-loved young-adult novel in the modern line, and Ciena is the reason. Most Star Wars fiction that puts a sympathetic character in an Imperial uniform eventually lets them defect. This one does not. It insists that a decent person, reasoning from decent premises, can spend a whole life on the wrong side.
Canon only
Ciena is a post-2014 creation with no Legends counterpart. The novel is unusual in tracking the films' events — Yavin, Hoth, Endor, Jakku — from beside them rather than inside them, which makes it a very good bridge for readers coming from the movies.
Reading note
Read it with Thane Kyrell's dossier. The book alternates between them and is designed so that neither is the villain.