Alice is a highly ambitious doctoral student in magick at Cambridge University. Overworked and deeply insecure about her position due to her lack of institutional privilege, she relentlessly pursues academic success at the expense of her physical and mental health, often withholding food from herself to achieve a state of intellectual purity. She holds herself responsible for a fatal mistake in a chalk pentagram that caused the death of her advisor. This guilt, paired with her desperate need for his recommendation letter to secure a tenure-track job, pushes her to undertake a dangerous descent into the underworld.

Peter is a brilliant, privileged Cambridge magick student and Alice's primary academic rival. Coming from a family of established scientists, he possesses a natural ease with the unspoken rules of the academic system. He frequently misses appointments, leading his peers to view him as an erratic genius, though his easy success continuously frustrates Alice. Despite their intense competition, he is highly attentive to Alice's personal boundaries and repeatedly checks on her well-being during their dangerous journey.

Jacob Grimes is a revered Cambridge magick professor whose career took off during World War II when he supplied the army with magical goods. He is notorious for his extreme demands, pushing his graduate students to prioritize intellectual discipline over basic human needs. His recent death, caused by a faulty chalk pentagram, leaves his students in precarious professional positions. He leverages his academic influence to manipulate his students, pitting them against one another and demanding absolute loyalty.

Nick and Magnolia Kripke are former American academics who were denied tenure for being too commercial and appealing to massive crowds. They famously performed a lethal stage stunt with their young son, Theophrastus, to enter the underworld intentionally and find a true contradiction to escape. Now reduced to dangerous figures, they violently hunt living magicians for their blood to cast powerful spells. They leave complex magical traps across the Courts and command animated skeletons made of bone and chalk.

Elspeth is a Shade and a former doctoral student of Professor Grimes who died by suicide ten years before Alice arrived at Cambridge. She retains a solid, beautiful form in the underworld by maintaining a strong mental image of her living self. She sails the Lethe river and acts as a guide to living magicians, offering them roasted rats for food and teaching them the unique rules of casting magick with blood in the underworld. She deeply resents the academic systems that contributed to her death.

John Gradus is an immaterial Shade residing in Dis, the final Court of the underworld. Unlike other Shades who obsessively write dissertations to justify their earthly sins, Gradus exhibits a profound curiosity about the living world. He asks travelers detailed questions about modern music, food, and city skylines. He provides crucial advice to Alice about the nature of the underworld and how to survive its dangers, rejecting the endless cycle of academic justification that traps his peers.

Lord Yama is the benevolent and just ruler of the underworld, taking the shape of Yanluo Wang—the god of death in Chinese culture—when Alice meets him. He observes the flow of souls and the machinations of the magicians who enter his domain with a sense of detached amusement. He enforces the rules of the afterlife but does not actively torture the Shades, who mostly trap themselves in recursive behavioral loops.

Archimedes is the living, analytical department cat from the Cambridge magick program. Because felines can naturally cross the veil between the living world and the afterlife, he wanders in and out of the underworld. He frequently appears to provide silent companionship to the traveling students, though he is easily frightened by the aggressive bone-creatures that roam the different Courts.

Old Lady Meng Po is the mythological guardian of the Lethe river. She enchants travelers who come near the water, tempting them with the alluring prospect of drinking its waters to forget their painful earthly memories. Her presence introduces the constant temptation for the characters to abandon their heavy psychological burdens.

George Edward Moore is a Shade residing in Pride, a library-like environment within the First Court. He volunteers to give Alice and Peter a tour, explaining that Shades there must answer philosophical prompts to move forward. He is easily distracted by logical premises, allowing the living students to slip away while he becomes lost in constructing academic arguments.

Weaver Girl is a Chinese mythological deity who followed her mortal lover to the afterlife, only to be left behind. She administers strict tests of loyalty to travelers who cross her path in the Third Court. She uses magical silk webs to enforce her rules, punishing those who fail her arbitrary relationship tests.

Gertrude is a Shade in the Eighth Court who firmly rejects the traditional methods of seeking reincarnation. She helps lead a community called the Rebel Citadel, where Shades attempt to find peace by taking root as trees and meditating indefinitely. She invites living travelers to abandon their quests and join the passive, silent community.

Helen Murray is another professor in the Cambridge magick department. She represents the rigid, unsympathetic institutional response to student struggles. When Alice approaches her with serious concerns about her treatment in the program, Helen advises her to simply endure the difficult situation and finish her studies rather than causing disruptions for the university.