Harlow is the youngest daughter of the ruling Carrenwell family in the walled city of Lunameade. She possesses a magic blessing from the Divine Harvain that causes her kiss to kill instantly. Forced into an arranged marriage with the heir of a rival fort, she secretly operates as the "Poison Vixen," a vigilante who targets abusive men. She suffers from chronic pain episodes and hides physical and emotional scars resulting from her harsh upbringing.

Henry is the heir to the ruling family of Mountain Haven. He carries deep resentment toward the Carrenwell family following the destruction of his home ten years prior. Possessing healing magic from the Divine Elvodeen, he initially views his arranged marriage to Harlow as a strategic move. He acts fiercely protective of his people and is dedicated to securing his family's future against outside threats.

Aidia is Harlow's older sister and the wife of Lunameade's mayor. She endures severe domestic violence, which she often refuses to hide completely. Her suffering drives Harlow's vigilante mission. Aidia shares a deeply protective bond with her sister and serves as Harlow's emotional anchor in their oppressive family environment.

Rafe is the powerful mayor of Lunameade and Aidia's husband. He possesses manipulation magic from the Divine Polm, which he uses to maintain his political dominance. He presents a charismatic public image that conceals his abusive and cruel private behavior. His actions directly motivate Harlow's secret life as a vigilante.

Kellan is Harlow's favorite older brother and the captain of the Lunameade city watch. He wields powerful compulsion magic. He is tasked with investigating the city's vigilante murders while trying to protect his sisters from their harsh family dynamics. He balances his duty to the city guard with his genuine concern for his siblings.

Harrick is the ruling patriarch of Lunameade and the head of the Carrenwell family. He wields holy fire magic and prioritizes his family's political dominance above all else. He treats his children as assets to secure alliances, maintaining strict control over them through fear and manipulation.

Liza is the matriarch of the Carrenwell family. She possesses retro-cognition magic that helps uncover the secrets of political rivals. She prioritizes public appearances and the family's power over the well-being of her children, consistently enabling her husband's strict and calculating methods.

Gaven is Harlow's lifelong bodyguard. He is a quiet observer who struggles to balance his loyalty to the Carrenwell parents who employ him and his protective duty toward Harlow. His presence provides Harlow with a constant shadow as she travels through dangerous political and supernatural environments.

Bea is the pragmatic owner of the Guardian's Crossing pub. She acts as an accomplice for Harlow's vigilante work, vetting clients and providing a safe operational base. She grounds Harlow by offering a rare, genuine connection outside of the highborn magical families.

Able is Harlow's older brother, who is suffering from a rapidly deteriorating mental state. His family suspects his condition is linked to his heavy use of the family's magical well to power city defenses. His decline adds urgency to Harlow's political mission.

Philip is Henry's father and the patriarch of Mountain Haven. He focuses on rebuilding his fort's strength following a devastating attack ten years prior. He views the alliance with the Carrenwell family as a necessary, if distasteful, step for survival.

Evangeline is Henry's mother and the matriarch of Mountain Haven. She possesses rare magical abilities and is fiercely protective of her remaining family. She participates in the strategic planning for the fort's future while keeping a watchful eye on Henry's emotional state.

Carter is a huntsman and one of Henry's closest friends in Mountain Haven. He acts as a voice of reason within their group, offering level-headed advice and participating in reconnaissance missions within Lunameade.

Bryce is a huntsman and a trusted friend of Henry Havenwood. He assists with intelligence gathering and security for their group. He is quick to appreciate Harlow's combat skills and presence, often adding levity to tense situations.

Stefan is a resident of Mountain Haven who harbors deep suspicion toward Harlow and resentment toward Henry's leadership decisions. He frequently challenges Henry's authority and actively attempts to provoke Harlow, escalating tensions within the fort.

Nicolina is a storyteller and resident of Mountain Haven who entertains patrons at local taverns. She possesses extensive knowledge of local lore, poisons, and magical theory, eventually providing Harlow with crucial information about the contaminated wells.