Viv is a young museum assistant in Astera living a secret double life as an aeon, a rare hunter cursed with an intense bloodlust. She struggles with her identity, viewing herself as somewhat monstrous. She keeps her vigilante activities hidden from her family and friends. After a chance encounter, she is invited to attend the secret Harker Academy for Deviant Defense.

Reid is a former Brood demon who serves as a combat instructor at Harker Academy. He bears the brand of the dark cabal but actively fights against his own kind. To maintain his ethical code, he denies himself human souls, a choice that limits his demonic power. He presents a controlled exterior to weather the suspicion of his peers.

Dean Driscoll is the legendary warlock who runs Harker Academy for Deviant Defense. He projects a stern, no-nonsense authority over the campus and its hidden history. He demands excellence from his recruits and famously advises his students to focus purely on survival.

Deacon is a powerful, unbranded demon who runs a criminal empire from his South of the Chasm nightclub, Fever Dream. Known in the underworld as the White Stag, he is charismatic and dangerous. He operates outside the direct control of the demonic cabal while maintaining significant influence.

Sophia is a vivacious and highly skilled student at Harker Academy. She embraces her life with unapologetic boldness and immediately extends a warm welcome to her new roommate. Unlike more guarded hunters, she provides a model of how to exist in the supernatural world without succumbing to isolation.

Peter is an earnest and intelligent young hunter recruited to Harker. Raised in the mundane world after his mother was killed by a demon, he is eager to learn about his heritage. He acts as the intellectual anchor for his friend group and frequently provides essential knowledge about the supernatural world.

Elliot is an athletic, good-natured student at Harker who comes from a large family of hunters. He enjoys the physical challenges of his training and approaches his duties with straightforward confidence. He quickly welcomes new students into his social circle.

Penny is Viv's best friend and roommate in the Babylon district. Kind-hearted and completely unaware of the supernatural reality of Astera, she provides Viv with unconditional love and stability. Their relationship represents Viv's primary tether to the mundane world.

Fiona is Viv's stressed, high-strung sister-in-law and her supervisor at the prestigious Windsor Museum. She pressures Viv to conform to the family's professional expectations. She manages the daily operations of the museum's historical exhibits with intense focus.

Professor Lisette is a severe academic at Harker Academy who teaches Underworld Studies. She is deeply knowledgeable about the hierarchies of deviants and the history of the Chasm. She strictly enforces the academy's rules and occasionally delivers cryptic warnings to students.

James is Penny's wealthy, socially conscious older brother and Viv's current boyfriend. He belongs to the affluent world North of the Chasm and frequently dismisses working-class areas. His relationship with Viv serves largely to appease her mother's desire for respectability.

Beatrice is Astera's district attorney and Viv's highly critical mother. She strongly disapproves of Viv living in the working-class Babylon neighborhood and pushes her toward a more respectable life. Her political ambitions often take precedence over emotional connection with her children.

David is Viv's late father and a former hunter who raised her to understand the supernatural world. His murder by the Brood cabal serves as Viv's primary motivation. He left behind powerful silver artifacts and hidden connections to Harker Academy.

Nora is Viv's older sister. Emotionally distant and aligned with their mother's upper-class expectations, she frequently dismisses Viv's frustrations. She maintains a safe, conventional life away from the dangers of the Half City's underworld.

Kitty is Peter's cousin and a focused first-year student at Harker Academy. She takes her training very seriously and is quickly recognized as a skilled fighter. Her abrupt disappearance from campus sparks a dangerous investigation among her peers.

Hound is Viv's pet dog, living with her and Penny in their apartment in the Babylon district. He provides a small source of comfort and normalcy in Viv's otherwise chaotic life.