Emil is a sensitive and observant student attending a local Latin school. Raised in a devout Christian household, he initially views the world in strictly black-and-white terms of light and darkness. He feels intense curiosity about the darker, forbidden aspects of life outside his home. As he matures, he searches for a personal identity independent of traditional societal and religious expectations.

Max is an older adolescent who behaves with the confidence and seriousness of an adult. He possesses a broad knowledge of philosophy and religion, regularly questioning traditional teachings. His alternative interpretation of the biblical story of Cain and Abel deeply impacts Emil. Max acts as a spiritual mentor, consistently challenging Emil to think independently and observe human behavior closely.

Frau Eva is Max Demian's mother, an intelligent and captivating woman who deeply understands the philosophical concepts her son studies. She provides a welcoming, intellectually stimulating environment in her home for individuals who bear the "mark of Cain." She acts as both a maternal figure and an object of deep reverence for Emil.

Franz is an older boy from the neighborhood who attends public school and comes from a lower-income background. He uses intimidation and blackmail to assert power over other children. When Emil lies about committing a theft, Franz immediately uses the opportunity to extort money and demand humiliating favors.

Sinclair's Father is a well-to-do, pious man who enforces traditional Christian values within his household. He demands cleanliness, order, and strict adherence to an established moral code. He expects his son to maintain a respectable image and struggles to understand Emil's rebellious phases, pushing his son to seek outside guidance.

Sinclair's Mother represents the domestic warmth and safety of Emil's childhood home. She maintains the family's religious harmony and provides a protective, loving environment. Emil views her as a symbol of the purity he feels he loses after telling his first significant lie.

Emil's sisters exist comfortably within the safe, religious boundaries of their parents' home. They serve as a contrast to Emil, as they do not feel the same pull toward the darker, forbidden elements of the outside world. Their polite distance from him during his rebellious phase emphasizes his growing isolation.

Pistorius is a former theology student who now works as a church organist. He possesses a deep knowledge of ancient mysteries, Romanticism, and the deity Abraxas. He spends time sitting by the fire with Emil, engaging in long philosophical discussions and helping the younger student interpret his complex dreams.

Beatrice is a young woman who unintentionally catches Emil's eye during his rebellious phase at boarding school. Emil never learns her real name or speaks to her, opting instead to name her after a figure from Dante's poetry. Her graceful appearance inspires him to stop drinking, focus on his studies, and begin exploring visual art.

Alfons is an older student at Emil's boarding school. He is experienced in the rebellious activities of the nearby town, including drinking and visiting local women. He introduces Emil to alcohol, momentarily acting as a mentor in the ways of adolescence, though his influence eventually causes Emil significant academic trouble.

Knauer is an anxious student who is obsessed with maintaining physical and spiritual purity. He struggles with his own urges and frequently seeks out Emil for advice, treating him as a source of wisdom. His intense need for guidance creates tension, as Emil remains reluctant to act as his mentor.