Lilia is a twenty-year-old medical student from a working-class background who works as a hospital cleaner to afford her younger sister's special schooling. Haunted by her mother's gruesome and unexplained death, Lilia centers her life entirely around caring for her sister and investigating the disease that tore their family apart. When she receives an unexpected scholarship to the elite Dracadia University, she takes the opportunity to study the parasite at its source, despite feeling intensely out of place among the wealthy student body.

Devryck is an intimidating parasitology professor at Dracadia University who comes from a wealthy, controversial family of scientific researchers. He suffers from a rare neurological condition triggered by severe childhood abuse, which causes life-threatening seizures and a chronic inability to feel physical sensation in his limbs. He operates a private, clandestine laboratory where he researches the Noctisoma parasite, hoping to synthesize a toxin that will cure his affliction before it kills him.

Lippincott is the powerful and image-obsessed provost of Dracadia University who gained much of his wealth and influence through marriage. A former researcher himself, he now controls the administration and funding of the science departments, prioritizing donor money and university prestige over academic integrity. He is deeply entangled in the university's historical cover-ups and is highly suspicious of anyone who might disrupt his path to becoming the university president.

Warren is Devryck and Caedmon's father, a prominent but disgraced scientific researcher who once led the infamous Crixson Project at Dracadia. He blamed Devryck for his wife's death during childbirth and subjected his son to brutal physical abuse. His unethical studies on the Noctisoma parasite resulted in multiple missing persons and deaths, leaving a dark legacy that dictates his family's reputation to the present day.

Caedmon is Devryck's twin brother, primarily existing as a tragic figure in Devryck's past. Growing up under the shadow of their abusive father, Caedmon often acted as a buffer and source of comfort for Devryck. His kidnapping as a teenager, which occurred because kidnappers targeted him over his ill brother, remains the defining tragedy of Devryck's life.

Francesca is Lilia and Bee's mother, a woman who suffered a harrowing, violent death four years prior to the main narrative. Her bizarre symptoms, which included extreme aggression, strange cravings, and coughing up black worms, deeply traumatized Lilia. Her passing serves as the primary catalyst for Lilia's fierce dedication to medical research.

Beatrix, often called Bee, is Lilia's twelve-year-old half-sister. Following the horrific trauma of her mother's death, Bee developed severe mental health issues that require specialized care at an expensive boarding school. She remains largely separated from the main events at Dracadia but functions as Lilia's primary motivation for securing money and succeeding academically.

Conner is Lilia's stepfather and Bee's biological father. He works sporadically as an unofficial handyman for their apartment building while engaging in shady business deals to make ends meet. He fails to provide adequate financial or emotional support for his daughters, often turning a blind eye to the dangerous people he brings into their home.

Angelo is Conner's morally bankrupt business partner who claims to sell scrap metal but actively participates in organized crime. He uses his proximity to Conner to frequently terrorize and sexually harass Lilia in her own home. His looming threat forces Lilia to leave her apartment and accept the scholarship at Dracadia to secure her safety.

Dr. Loretta Gilchrist is the chair of the natural science department and the entomology professor at Dracadia. Following Devryck's decision to end their secret affair, she becomes intensely jealous of Lilia's placement in his advanced course. She wields her academic authority as a weapon, openly condescending to Lilia regarding her working-class background and actively trying to sabotage her education.

Spencer is a student at Dracadia and Provost Lippincott's son. He serves as a teaching assistant for Dr. Gilchrist and quickly takes an interest in Lilia, persistently asking her out despite her clear boundaries. Although he presents himself as charming and friendly, his actions often blur the lines of consent, and he carries intense bitterness regarding his miserable relationship with his father.

Melisandre, known as Mel, is the resident assistant for Lilia's floor in Corbeau Hall. The daughter of the university's chairman, she dresses eccentrically and holds a cynical view of Dracadia's wealthy white patriarchal structures. She belongs to Anon Amos, a secret student group dedicated to unearthing the university's hidden conspiracies, and takes it upon herself to warn Lilia about the dangers posed by Devryck and Spencer.

Mr. Barletta is an abusive fugitive who fled to Dracadia under the false promise of safe passage out of the country. Devryck kidnaps him, locks him in a 1700s prison cell beneath the university, and secretly infects him with Noctisoma parasites to study the live progression of the disease.

Jayda is Lilia's dependable coworker at the hospital. Understanding the immense financial pressure Lilia faces to care for her sister, Jayda orchestrates a collection from the hospital staff to pay Bee's tuition, effectively allowing Lilia the freedom to accept the Dracadia scholarship. She frequently urges Lilia to break out of her restrictive lifestyle and be audacious.

Dean Langmore is the administrative head who grants Lilia a sudden, full-ride scholarship to Dracadia University for the fall semester. He pushes for Lilia to be placed directly into advanced parasitology courses based on the brilliance of her theoretical paper, putting him at odds with other university officials who prefer traditional enrollment protocols.

Briceson is a sophomore studying chemistry and theater at Dracadia. He serves as Lilia's first introduction to the student body, eagerly sharing the local ghost stories and campus superstitions surrounding the island's dark colonial history as they travel to the school.

Jenny is a Dracadia student who vanished two years prior to Lilia's arrival. Her disappearance hangs over the campus like a dark cloud, spawning intense rumors that heavily implicate Devryck Bramwell, as she was allegedly last seen on security footage entering his laboratory.