Aurienne is a skilled healer of the Haelan Order who serves as the director of Swanstone’s Centre for Seith Research. Capable of removing seith clots without surgery, she holds a highly prestigious reputation in the medical community. She initially presents herself as a strict rule-follower who keeps emotionally distant from her patients, though her deep academic curiosity pushes her toward researching forbidden magical practices to cure supposedly untreatable diseases. She possesses a notoriously sharp tongue that she directs at anyone acting immorally.

Osric is a deadly assassin walking the Dusken Path within the secretive Fyren Order. Suffering from a degenerative condition called seith rot, he faces immediate execution from his own faction if his failing magic is discovered. He holds the illegitimate title to his family's fallen estate, Rosefell Hall, masking a highly abusive past with swaggering arrogance. Despite his unapologetic career in murder, he harbors an unexpected protectiveness toward discarded animals and his loyal servants.

Xanthe is the pragmatic, 200-year-old director of the Haelan Order's Swanstone headquarters. Faced with a horrific viral epidemic and completely apathetic monarchs, she exhibits extreme political shrewdness to secure funding for a vaccine. She recognizes Aurienne's medical genius and actively pushes the younger healer to bypass standard research protocols for the greater good.

Lord Wellesley is a wealthy Wessexian nobleman who resides in a highly illuminated keep specifically designed to ward off shadow-walking assassins. He wields his noble status to manipulate the Haelan Order for personal gain and information. He involves himself in massive political conspiracies surrounding the current viral epidemic.

Tristane serves as the London-based war chief of the Fyren Order and holds the reputation of being their single deadliest member. She is a greedy, merciless leader of French origin who strictly enforces the rule that assassins must show absolutely no conscience. She trains her operatives from childhood and actively seeks highly lucrative contracts that violate international peace treaties.

Mrs. Parson is the highly resourceful steward of the Mordaunt family and the only remaining servant operating Rosefell Hall. She commands a vast, quiet network of informants working as servants across the Tīendoms. Having protected Osric from his abusive father during his youth, she acts as a deeply supportive maternal figure entirely unfazed by his violent profession.

Sacramore serves as the second-in-command of the Fyren Order under Tristane. Operating out of the Order's current stronghold disguised as a pharmacy, Sacramore manages the daily flow of dangerous intelligence and assassination contracts.

Brythe is a ruthless assassin within the Fyren Order. He holds a violent history with Osric, having caused the initial spinal injury that triggered Osric's magical degeneration. He actively pursues dangerous assignments on behalf of Tristane and harbors no reservations about breaking the standing Peace Accords between factions.

Lady Windermere is a deadly operative within the Fyren Order. She works closely with her lover, Brythe, operating with the same ruthless efficiency expected of Tristane's followers.

Cíele is Aurienne's animal familiar, or deofol. Providing companionship and functioning as a magical messenger, Cíele perfectly mirrors Aurienne's acerbic temperament when dealing with undesirable individuals.

Cinder is Osric's animal familiar, manifesting as a she-wolf formed entirely of smoke and shadows. She acts as a discrete messenger for the assassin, easily navigating the dangerous boundaries between warring Orders.

Leofric is a boisterous colleague of Osric's within the Fyren Order. He loudly considers himself Osric's best friend, a title Osric vehemently denies. He frequently interrupts highly sensitive moments with his crass and uninhibited behavior.

Scrope is an unsavory, leering man who frequents the filthiest pubs in the Tīendoms. He acts as an information broker in the criminal underworld, holding valuable knowledge regarding secret attacks on the Haelan Order.

Radia is Aurienne's mother, an immensely successful engineer whose recent invention elevated the family to nouveau riche status. She originally hoped Aurienne would follow her into engineering rather than the grueling healing arts.

Rosbert is Aurienne's father. He lives a comfortable, protected life thanks to his wife's engineering success and happily hosts large gatherings, entirely unaware of the dangerous political currents his daughter faces.

Cath is a highly skilled surgery expert within the Haelan Order and one of Aurienne's closest friends. She offers discrete medical advice when Aurienne requires off-the-record surgical knowledge for complicated injuries.

Élodie is a dedicated researcher and Haelan colleague who works tirelessly on developing a viable vaccine for the Platt's Pox epidemic. She brings rare moments of hope to the overwhelmed medical staff through her scientific breakthroughs.

Widdershins is a disgraced former philologist whose theoretical research on the Old Ways of healing provides the blueprint for Osric's cure. He lives in rural isolation, presenting a highly disorganized, "pixie-led" exterior to deter anyone asking about his past work.

Aedan is Aurienne's former romantic partner. According to Aurienne, he was entirely too flawless and lacked the character faults necessary for a compelling long-term relationship, leaving him pining for her after their separation.

Quincey is Aurienne's administrative assistant at Swanstone. He harbors an obvious infatuation with his boss and attempts to keep her strictly monitored within the safety of the fortress walls.

Pipplewaithe is the attentive chamberlain of Wellesley Keep. He executes his lord's commands with precision, treating Haelans with the utmost respect while pointedly dismissing the presence of heavily armed Wardens.

Amagris is a secretive Hedgewitch and a former romantic partner of Aurienne. Their past relationship represents Aurienne's history of pursuing complicated, taboo attachments outside the safety of her own Order.

Noldo is a former assassin of the Fyren Order who refused to complete a contracted kill. His decision to grow a conscience earns Tristane's fatal wrath, demonstrating the Order's zero-tolerance policy toward morality.