Greyson Serel, known as Grey to his family and friends, is one of the protagonists of Daggermouth. Greyson is the son of Maximus Serel, the president of New Found Haven. He has been conscripted by his father to serve as the city state’s Executioner, a role he resents. Nearly every day, Greyson is required to execute people who transgress the rules of New Found Haven even in minor ways. When he hesitates to do so even briefly, he is severely punished by his father, who seeks to control every aspect of Greyson’s life.

Greyson struggles with self-loathing and hopelessness due to the many deaths he has caused. When Shadera comes to assassinate him, he removes his mask, a taboo in the Heart, and encourages her to do so, as he believes that his death may cause more good than harm. He resists his father’s control by smuggling medicine from the rich Heart district to the poor outer districts. He keeps these activities secret to protect those he loves, though he later learns that his best friend, Callum, and his sister, Lira, both also resist Maximus’s rule in their own ways. Over the course of the novel, Greyson must learn to trust his friends and allies. Greyson also comes to increasingly admire and later love Shadera.

For much of the novel, Greyson looks up to his elder brother, Brooker, whom he believes to be dead. He seeks to find his brother’s murderer, whom he has been led to believe is one of the Daggermouth assassins. When he believes that Shadera was the one to kill Brooker, he struggles between his loyalty to his brother’s memory and the growing connection that he and Shadera have formed. Even before he learns that Brooker’s death has been faked, he reaches an uneasy peace with Shadera, whom he still cares for and trusts. Greyson is highly motivated to protect the people he loves; he agrees to marry Shadera because Maximus threatens Callum and Lira. His father exploits this “weakness” by beating Shadera while Greyson is forced to watch, a torture he finds more difficult to bear than being beaten himself.

At the end of the novel, Greyson admits to himself that he wants to marry Shadera. The status of their relationship is uncertain at the end of the text; they are bound in the Vow ceremony, but the peace between them is tenuous.

Maximus Serel is the totalitarian president of New Found Haven and the novel’s primary antagonist. He is the putative father of Greyson, Lira, and Brooker, but Greyson later learns that Maximus is not his biological father. This reveal adds complexity to Greyson’s feelings about the brutal man who raised him.

Maximus is a flat, static antagonist with no redeeming qualities. A vicious dictator, he is also and an abusive father and husband. He cruelly beats Greyson in the name of training, confines Elara in painful bondage when she disobeys him in any way, and arranges for his daughter to be raped by senior commanders in the Veyra army. Maximus is entirely unrepentant regarding these actions, despite his continued insistence that he loves his family. He justifies this abuse as the cost of maintaining his power, but his actions make clear that he takes pleasure in hurting others. He shows no limits to the violence he is willing to commit in order to keep his totalitarian control over New Found Haven. Maximus’s surveillance state keeps him informed of the rebel movements throughout the outer rings of the city, so he is able to plan for the rebels’ attack in the novel’s climax. His misogynistic dismissal of women in general and his own wife and daughter in particular, however, lead him to underestimate Elara and Lira, whose rebellions surprise him. Elara kills him as part of the novel’s cliffhanger ending.

Brooker Serel is Maximus’s eldest son, and Lira and Greyson’s brother. For much of the novel, Brooker is presumed dead. Later, when he reveals himself to be alive, he claims to have faked his death so that he can serve as part of the rebellion against his father. In the novel’s climax, however, he further reveals that he is actually a double agent sent by Maximus to infiltrate the rebels. When the rebels attack the Heart, Brooker feeds Maximus information to undermine their plans. At the end of the novel, Brooker kidnaps Lira after killing Callum, which sets him up to be a primary antagonist in the next installment.

Brooker’s supposed death is a plot device in the novel, generating both a source of mystery and tension between Greyson and Shadera. Greyson seeks to find his brother’s killer; when Shadera learns that she attacked (and assumes she has killed) Brooker under a false name, Greyson struggles to forgive her. The pair come to an understanding that brings them together even before Brooker is revealed to be alive and loyal to Maximus.

Lira Serel is Greyson’s sister and the daughter of Maximus Serel. Lira works in public relations in New Found Haven, and her skill in developing propaganda becomes a useful tool for the rebels when they seek to unseat Maximus. Lira, despite her apparent privilege, has experienced some of the most brutal violence of New Found Haven; she reveals that her father arranged for her to be serially raped by senior commanders in his army, using misogynistic ideology to justify this abuse. Lira becomes a strong defender of New Found Haven’s women due to this history, and organizes a group of women, all survivors of intimate partner violence, to protest Shadera and Greyson’s Vow ceremony after she learns that Maximus intends for Shadera to be raped by Veyra commanders.

Lira is frequently angry with her brother and her love interest, Callum, for keeping secrets in the name of protecting her. She also resents it when Callum centers himself and his inability to protect her after he learns about her experience with sexual violence. She asserts that her ability to survive in a vicious, sexist system had made her strong, not weak. At the end of the novel, Lira is captured by Brooker, her fate left unknown after the cliffhanger ending.

Callum Thane is Greyson’s best friend, Lira’s love interest, and the most powerful business owner in the entertainment realm in New Found Haven’s Heart district. Callum runs a club where many sex workers operate; he is fiercely protective of these women and seeks violent retribution against anyone who harms them. He collects secrets against the powerful people of the Heart, which he then feeds to the rebels who operate in the outer districts of the city.

Callum has long been in love with Lira Serel, but he pushed her away, fearing that a romance between them would damage his relationship with Greyson. Eventually, Callum admits to his feelings for Lira, and the two admit their love for one another. Callum is very protective of Lira, and he feels extreme guilt when he learns that she was sexually assaulted. Lira rejects this guilt, viewing it as unwanted male overprotectiveness. Callum is a talented hacker, skills that he deploys to aid the rebels. In the climax of the novel, he is killed by Brooker.