Agnes is a 24-year-old English teacher living in Athens, Ohio, in 1995. She considers herself completely ordinary in contrast to her late teenage sister's fantasy interests. Currently preparing to move in with her boyfriend Miles, Agnes discovers a Dungeons and Dragons module left behind by her sister. She decides to play the game to understand the sibling she feels she never truly knew.

Agnes's 16-year-old sister who died in a car crash. In the Dungeons and Dragons community, she is known as a respected Dungeon Master and the fearless character Tillius the Paladin. She creates the fantasy world of New Landia as an imaginative escape from her real-world experiences as an isolated youth in a small Ohio town.

Agnes's boyfriend of three years. He expects Agnes to move into his apartment and struggles to understand her sudden preoccupation with her late sister's belongings. He acts defensive and jealous when he misunderstands Agnes's interactions with Chuck. His underlying goal is to share a life with Agnes.

A teenage grunge-rocker roadie and clerk at a local gaming store. He serves as the Dungeon Master for Agnes's playthrough of Tilly's campaign. He possesses extensive knowledge of role-playing rules and acts as the narrator for the fantasy sequences in New Landia. He translates Tilly's notes into a playable adventure for Agnes.

In the game, Lilith is a fierce Demon Queen who fights alongside Tillius. In reality, Lilly is a high school student who knew Tilly before the car accident. Lilly carries a letter from Tilly and deals with her own teenage anxieties while trying to maintain her privacy when Agnes confronts her at school.

A caustic high school guidance counselor who works with Agnes. She openly voices her low opinion of teenagers and actively discourages students from bothering her unless they are failing. She frequently criticizes Miles for his reluctance to propose to Agnes.

A dark elf and agile tracker in Tilly's Dungeons and Dragons party. She assists Tillius on the quest to recover a lost soul. Her real-world counterpart is Kelly, a teenager with cerebral palsy who shares Tilly's passion for role-playing games.

The red-skinned, horned demon of the underworld in New Landia. Despite his frightening appearance, he prefers watching television shows over acting as a villain. He trades away a lost soul for a TV unit and is forced to join Tilly's party to retrieve it.

A high school student who occasionally seeks academic advice from Vera. In the fantasy world, he appears as the adventurer Mage Steve, who frequently and violently dies within moments of entering a scene.

A succubus in New Landia who appears dressed as a stereotypical cheerleader. She relentlessly attacks and belittles Tillius and Agnes in the fantasy world. She represents the real-world bullying Tilly faced at school.

Another succubus dressed as a cheerleader who operates alongside Evil Gabbi. She uses physical intimidation and mockery to overpower her targets in the Dungeons and Dragons module.

A singing and dancing faerie who lives in the woods of New Landia. She appears delicate but possesses lethal combat skills. She serves as a ruthless guardian who attacks Tilly's party.