Arwen is a healer from the town of Abbington in the Kingdom of Amber. She possesses a rare magical ability to heal wounds by drawing power, though she hides the full extent of this talent from the wider world. Dedicated entirely to caring for her ill mother and younger sister, she routinely puts her family's needs before her own safety and desires. Her deep-seated anxieties keep her tethered to her hometown until her brother's sudden return forces her into captivity.

Kane is the imposing and widely feared King of Onyx. Rumored by the citizens of Amber to be a bloodthirsty and ruthless monster, he leads his kingdom in a brutal war. When he first meets Arwen in the dungeons, he conceals his true identity, appearing only as an attractive, cynical prisoner. He operates with a strict philosophy that mercy and love are weaknesses for a ruler, though he exhibits unexpected moments of vulnerability.

Halden is Arwen's childhood best friend from the Kingdom of Amber. With his fair hair and easy charm, he represents the safety and familiarity of Arwen's past life in Abbington. After being conscripted into King Gareth's army, he disappears for over a year, leaving Arwen clinging to the hope of his safe return. His time in the military alters his personality in ways Arwen struggles to reconcile.

Mari is an energetic, red-headed resident of Shadowhold who quickly befriends Arwen. She provides a sharp contrast to the grim atmosphere of the Onyx keep with her overly chatty nature and intellectual curiosity. Endlessly researching old lore and ancient magic, she offers Arwen companionship and valuable information about the castle and its inhabitants.

Dagan is a gruff, older war veteran who now works in the Onyx apothecary. Once a military advisor, he prefers a quiet, withdrawn existence and initially treats Arwen with distant toleration. Despite his surly exterior and the rumors that he is a warlock, he possesses a protective nature and agrees to teach Arwen self-defense.

Ryder is Arwen's charismatic, outgoing older brother. Eighteen months prior to the story, he was conscripted into the Amber military alongside Halden. His sudden return as a deserter, carrying stolen Onyx coin, forces his family to flee their home and sets off the chain of events that leads to Arwen's capture.

Leigh is Arwen's fearless and reckless younger sister. She relies heavily on Arwen's care and protection in their small town of Abbington. Her idealism and lack of caution constantly worry Arwen, who fears Leigh will end up drafted into the war or hurt by her own daring nature.

Mrs. Valondale is Arwen's ailing mother, suffering from an unidentified sickness that leaves her weak. Her declining health is a constant source of anxiety for Arwen, who dedicates her life to finding treatments and managing her mother's care while holding the family together.

Griffin is King Kane's surly and highly capable second-in-command. He is one of the few high-ranking officers who maintains his position long-term within the brutal Onyx military structure. Fiercely loyal to Kane, Griffin handles the harsh realities of military discipline and views Arwen's presence at the keep with skepticism and irritation.

Lieutenant Bert is a ruthless officer in the Onyx military who tracks Ryder to the Valondale home. He captures Arwen and brokers the deal that brings her to Shadowhold as a healer. He represents the cruel and violent stereotypes of the Onyx army, utilizing intimidation and force to maintain control.

Barney is an Onyx soldier whose life Arwen saves with her healing magic, establishing her worth to the enemy army. After arriving at Shadowhold, he is assigned as Arwen's primary guard, escorting her between the dungeons and the apothecary while keeping a watchful eye on her movements.

King Gareth is the ruler of the Amber Kingdom, leading the war against Onyx. While his citizens believe him to be a just, generous, and moral leader protecting them from foreign aggression, whispered rumors and enemy perspectives suggest he operates with a hidden, power-hungry agenda that endangers his own people.

Powell is Arwen's late stepfather, a cruel man who regularly inflicted physical abuse on her during her childhood. Though he died years ago from a stroke, the trauma of his punishments leaves Arwen with severe claustrophobia and deep emotional scars.

Nora is a trusted family friend and resident of the Amber Kingdom. She functions as a reliable assistant to Arwen during complicated medical procedures, offering support as Arwen tends to the wounded and sick citizens of their deteriorating town.

Jaem is the butcher's son at Shadowhold. Smitten with a young woman, he secretly runs leftover meat into the nearby town at midnight to earn extra coin. His covert nightly trips inadvertently provide Arwen with an opportunity to attempt an escape.

Lucinda is a young woman living near Shadowhold who has captured Jaem's affections. She is the primary motivation for his risky midnight trips to town.

Owen is a middle-aged resident of Shadowhold and the father of Mari. His minor injuries prompt Arwen's first independent healing task under Onyx supervision.