Elisabeth is a tall, physically strong apprentice who was found on the library steps as an infant and raised among sentient grimoires. Her lifelong exposure to the magical texts gives her a unique resistance to magic and a deep, empathetic connection to the books. Sheltered by the library's strict teachings, she dreams of becoming a warden but struggles with a deep-seated fear of sorcerers.

Nathaniel is an eighteen-year-old sorcerer who has already attained the prestigious rank of magister. He has a pale complexion, light gray eyes, and black hair with a streak of silver marking his demonic contract. Fearing his infamous family legacy and the trauma of his relatives' deaths, he isolates himself from society while hiding behind a cynical, playful exterior.

Silas is a powerful demon contracted to serve Nathaniel. He adopts the meticulous demeanor of a traditional servant, completing all housekeeping tasks for Thorn Manor alone. He carries deep guilt regarding his past actions and views himself as a creature of pure evil, yet he demonstrates extreme loyalty and care for the Thorn family.

As the Chancellor of Magic, Ashcroft is the second most powerful person in Austermeer. He presents himself as a brilliant, charismatic philanthropist who wishes to modernize sorcery. He possesses thick blond hair and a crimson eye that marks his demonic contract, projecting the appearance of a storybook hero while wielding immense societal influence.

The Director of the Great Library of Summershall is an elegant, severe woman with ice-pale features and flame-red hair. She bears a severe facial scar from battling a monster in her youth. Governed entirely by the warden motto of duty unto death, she presents a strict exterior but acts as a quiet, steadfast protector to the foundlings in her care.

Katrien is an apprentice librarian at Summershall who wears spectacles and constantly scribbles notes on her arms. An orphan who began her training at age thirteen, she is rebellious, intensely curious, and highly knowledgeable. She frequently involves Elisabeth in pranks and experiments, bringing levity and loyalty to their friendship.

Finch is a strict and punitive warden at the Great Library of Summershall. He enforces the rules rigidly and assumes control of the library following a catastrophic attack. He is quick to assign blame to apprentices and rules through intimidation rather than guidance.

Lorelei is a demonic servant contracted to Chancellor Ashcroft. She takes the form of a woman with long black hair and red eyes. She utilizes her powers of glamour to control situations and assist her master in maintaining his pristine public image and hidden agenda.

Mistress Wick is the Deputy Director of the Royal Library in the capital city of Brassbridge. She values truth and a genuine love for knowledge, offering a more open-minded perspective on magic than the strict dogmas taught at Summershall.

Aldous Prendergast is a historical sorcerer whose consciousness resides within the Codex Daemonicus. Centuries ago, he claimed to have discovered a terrible secret in the demon realm, leading to his imprisonment and death. He is highly guarded and distrustful of visitors seeking his hidden knowledge.

Mercy is a kindhearted young nurse working at Leadgate Hospital, a grim psychiatric institution. Unlike the orderlies who use force and intimidation, Mercy displays genuine compassion for the vulnerable patients under her care.

Alistair is Nathaniel's deceased father, a sorcerer whose immense grief drove him to dangerous extremes. After losing his wife and younger son in an accident, he attempted to resurrect them using forbidden necromancy, an act that fundamentally altered his surviving family's future.