Galaxy Stern is an undergraduate student at Yale with a troubled history in Los Angeles. She serves as Lethe's Virgil, a role requiring her to oversee the magical rituals performed by the university's other secret societies. Her unique ability as a Wheelwalker allows her to see and channel the spirits of the dead, a power she relies on to survive supernatural threats. Driven by guilt, she remains determined to rescue her former mentor from hell at any cost.

Daniel Arlington V is the former Lethe Praetor and Galaxy's mentor, currently trapped in hell. Before his disappearance, he presented as a polite, intelligent gentleman with a deep love for New Haven's history and magical lore. His time trapped in the underworld severely strains his humanity, forcing him to fight dark influences as he tries to communicate with his allies in the mortal world.

Pamela Dawes is a graduate student and Lethe's Oculus, responsible for maintaining the organization's archives and magical resources. She prefers wearing oversized sweaters and headphones, usually avoiding direct confrontation. Her deep loyalty to Daniel pushes her to conduct dangerous research and perform illicit rituals to secure his rescue.

Abel Turner is a detective with the New Haven Police Department and Lethe's Centurion, acting as their official police liaison. He is a pragmatic, grounded officer who deeply distrusts the secret societies and their magic. Despite his skepticism, he gets pulled into Galaxy's dangerous plans when supernatural murders strike the Yale faculty.

Michael Anselm is a lawyer and member of the Lethe board who steps in as a temporary liaison for the students. He is highly critical of Galaxy and Pamela, demanding they abandon their search for Daniel. He uses his authority to enforce strict rules, threatening to strip the young women of their Lethe resources if they disobey his orders.

Mercy Zhao is one of Galaxy's roommates, an idealistic student initially unaware of the magical underworld. When she learns the truth about Yale's secret societies, her desire to do good pushes her to volunteer for dangerous tasks. She provides a naive but eager perspective that constantly clashes with Galaxy's cynical worldview.

Tripp Helmuth is a hapless former member of the Skull and Bones society who has fallen on hard times and failed to graduate. Cut off by his family, he struggles financially and lives on the margins of campus society. He agrees to help Galaxy's group with a dangerous ritual in exchange for payment and protection from his former society members.

Linus Reiter is a wealthy estate owner in Old Greenwich with deep ties to Yale's occult history. He presents a polite but unnerving demeanor that quickly gives way to extreme violence. He serves as a lethal obstacle for Galaxy, proving to be an adversary she cannot physically overpower.

Eitan Harel is a Los Angeles drug kingpin intimately connected to Galaxy's troubled past. He extorts her into acting as a part-time enforcer by threatening her mother's safety. He views Galaxy entirely as a useful tool for his criminal enterprise, forcing her into increasingly dangerous situations.

Hellie is Galaxy's deceased best friend from Los Angeles, whose tragic overdose severely traumatized Galaxy. She represents Galaxy's greatest failure and deepest regrets. Her memory serves as a constant reminder of the collateral damage caused by Galaxy's past lifestyle.

Raymond Walsh-Whiteley is an academic appointed as the new faculty liaison for Lethe. He holds sexist views about women at Yale and frequently questions Galaxy's background. He remains largely ignorant of the group's illicit, supernatural rescue efforts.

Michelle Alameddine is Daniel's former mentor. Having survived a near-death experience, she possesses firsthand knowledge of the spiritual realm. She attempts to warn Galaxy about the snares of the dead and provides her with crucial reading material regarding demonic forces.

Carmichael is Abel Turner's former police partner. He represents the systemic corruption within the police force and acts as the source of Abel's deepest professional and personal regrets.

Blake Keely is a deceased individual from Pamela Dawes's past. The memory of Blake heavily burdens Pamela, tying into the traumatic events she struggles to process.

Daniel Arlington is the father of Daniel Arlington V. He maintains a strained, highly critical relationship with his son and exerts immense pressure regarding the future of the family's Black Elm estate.

Harper Arlington is the mother of Daniel Arlington V. Alongside her husband, she attempts to force the sale of the Black Elm estate, creating significant tension within her family.

Spenser is Tripp Helmuth's cousin. He is tied to a traumatic sailing accident from their childhood, an event that deeply scarred Tripp.

Lauren is a Yale student who shares a living space with Galaxy and Mercy. She remains completely unaware of the supernatural dangers and magical secret societies operating around her.

Len is Galaxy's ex-boyfriend and a drug dealer from Los Angeles. He represents the darkest parts of Galaxy's past and serves as a violent physical threat during her time in California.