Princess Seraphena “Sera” Mierel is the protagonist of A Shadow in the Ember, and the novel is told from her first-person perspective. She is 17 at the novel’s start, but 20 for most of its events. She is described as having messy blonde curls that reach her hips, green eyes, freckles, and a crescent moon birthmark on her left shoulder that marks her as destined for Nyktos (Ash), the Primal of Death. Sera is defined by compassion, determined to protect her loved ones and those who cannot defend themselves, such as the common people losing their homes and livelihoods to the Rot. However, she is impulsive and has a short temper, this willingness to take risks being both a strength and a weakness. She is later revealed to possess an ember of life, bestowed on the Mierel bloodline by Eythos, the former Primal of Life. It gives Sera the ability to heal and revive the dead, making her the true Primal of Life.

As the first daughter of the Mierel bloodline, the royal bloodline of Lasania, Sera is subject to an ancient deal made by an ancestor to stop the Rot—by becoming the Consort of the Primal of Death.