Kaine Ferron is a primary character and Helena’s romantic counterpart. At the novel’s start, Kaine is introduced as a villain and appears to be the novel’s antagonist. Because the Resistance regards him as their enemy, so does Helena. She is shocked and disgusted when Ilva Holdfast and Jan Crowther ask her to work with Kaine and gain his loyalty by whatever means necessary. Over time, however, Kaine’s character softens. Kaine proves himself to be kind at heart. His cruelty and violence are symptoms of his trauma, rather than evidence of his innately wicked nature.

Kaine is also a dynamic character who changes over the course of the novel as a result of his experiences and relationships. Kaine has experienced rejection and hardship ever since he was a child. His father Atreus Ferron withheld warmth from him, and has blamed him for years for his wife Enid Ferron’s death. Kaine also holds himself responsible for his mother’s death. He tried to save her from Morrough, but failed. In the present, he is haunted by the torture his mother suffered at Morrough’s hands. Much of his desire to protect Helena begins with his desperation to atone for Enid’s death.

Kaine is a complex character who proves willing to sacrifice himself for a higher cause. He knows that he may have to die in order to defeat Morrough. He decides that he is willing to do so because otherwise Morrough might remain at large and continue destroying innocent lives and wreaking havoc throughout Paladia.

Helena offers Kaine redemption, hope, and healing. Helena literally saves Kaine’s life by helping to recover his soul from Morrough and returning it to Kaine’s body. However, she also fortifies him emotionally. Helena reminds Kaine that he is in fact good and deserving of love. He ultimately achieves a happy ending because of Helena’s devotion to him.

Morrough is the antagonist of the novel, and another primary character. Although he is central to the novel’s ongoing political conflict, Morrough does not often appear in scene. He is a shadowy figure who infuses the narrative atmosphere with fear, tension, danger, and impending violence. Morrough’s main objective is immortality. He is willing to do anything to keep himself alive. To remain in power, Morrough extracts living souls from his victims, places them into bones, and puts the bones into his own body. He also thrives off his endless horde of Undying followers.

Morrough causes upheaval for Helena and Kaine in more intimate ways, too. He experiments on Kaine throughout the novel, and later kidnaps and imprisons Helena. Ultimately, Lila Bayard kills Morrough and ends his reign of terror.

Lila and Soren Bayard are secondary characters. They are also Helena’s close friends. Helena meets the siblings when she first enrolls at the Institute. They are friends of Luc’s, and she joins their friend group. They remain close throughout their time in school and over the course of the war. Because of their personal history together, Helena is devastated when she fails to save Soren during a battle. He dies, and she tries unsuccessfully to reanimate him using necromancy.

Helena maintains a friendship with Lila despite having contributed to Soren’s death. Lila is bold and determined. She is invested in the Resistance, but closely identifies with Helena, too. Ultimately, she and Helena escape Paladia together with Kaine’s help. In Part 3, the friends create a life together on a small, secluded island. They raise their children together and find strength in their connection.

Luc Holdfast is another of the novel’s primary characters. He is the symbol of the Resistance. After Kaine kills Luc’s father, Principate Apollo Holdfast, Luc becomes the new prospective leader of the Eternal Flame. He fights against Morrough and the Undying, forever trying to uphold the principles of his forbear, Orion Holdfast.

Luc is also Helena’s close friend. Luc is one of the only people who reaches out to her when she first arrives at the Institute. Rather than dismissing her because she is a foreigner, Luc welcomes Helena into his friend group. The two remain close over the years. Helena is therefore infuriated when Kaine questions the authenticity of Luc’s feelings for Helena. He implies that Luc only cares about her because his family wants to use her for her vivimancy and animancy powers. Helena later determines that Ilva is indeed abusing Helena for her own gain, but that Luc is not a part of this scheme.

During the war, Morrough captures Luc and experiments on him. He extracts parts of Luc’s soul to empower himself. Luc has to die by suicide to disempower Morrough. Helena tries to save him but fails; she blames herself for his fate. She believes that if she hadn’t pulled away from Luc, she would have been more attuned to what he was going through. Luc’s death haunts Helena throughout the narrative present.

Jan Crowther is another of the novel’s secondary characters. He is a primary face of the Resistance. Helena initially trusts and respects him, but their relationship changes after Helena is excused from the Council. With the help of Ilva Holdfast, Jan uses and manipulates Helena. He forces her to liaise with Kaine to gain information about the Undying for the Resistance. He does not explain the real risks of or designs behind this political arrangement, and he constantly ridicules her for failing to fulfill her duties. Helena becomes increasingly limited by Jan’s power over her. She feels compelled to obey him because she is loyal to the Resistance. Over time, however, she realizes that Jan is only trying to protect himself by aligning himself with the Holdfasts—whose primary goal is to protect their name, reputation, and power in Paladia.

Aurelia is another of the novel’s secondary characters. She is Kaine’s wife. From a young age, Aurelia was promised to Kaine. Her parents used her to form an alliance with the Ferron family and guild. Aurelia has no genuine affection for her husband, but feels upset by his lack of attention and threatened by his interest in Helena. Aurelia’s cruelty toward Helena is a symptom of her isolation. Kaine is unkind to her and shows her no affection, effectively alienating Aurelia. She takes extreme measures to get his attention, including having affairs right under his nose or violently attacking Helena. Her character creates tension in the beginning chapters of the novel, complicating the reader’s understanding of Helena and Kaine’s dynamic.

Ilva Holdfast is also a secondary character. She is Luc’s aunt. Helena initially feels drawn to Ilva, who shows an interest in her when she first comes to the Institute. Helena misconstrues Ilva’s interest as kindness and compassion. In reality, Ilva only pays attention to Helena because of her marked powers. She is particularly intrigued by Helena because the Stone of the Heavens alloy responds to her in a way it never has to anyone else. Over the years, she gains Helena’s trust so she can manipulate her powers for her own gain. Ilva is most interested in hiding the truth about the Stone from Paladia. She does want to defeat Morrough, but more than that, she wants to recover the Stone so she and her family can maintain power and authority.