Marigold is a twenty-one-year-old woman who feels out of place among her artistic, high-society family in Bardshire. Drawn to nature and magic rather than marriage, she accepts her destiny to become the Honey Witch of Innisfree, taking on the responsibility of protecting the isle. To claim her magic, she agrees to a family curse that demands she forsake romantic love, a sacrifice that grows complicated as she settles into her new life.

Lottie is a striking, red-haired woman with a prickly exterior and a staunch refusal to believe in magic. Having lost her parents in a fire at a young age, she grew up on the streets before being taken in by August's family. She covers the burn scars on her arms with intricate tattoos, a taboo practice for women in this society, and acts fiercely protective of those she cares about.

Althea is Marigold's one-hundred-year-old grandmother and the aging Honey Witch of Innisfree. She is wise, dutiful, and fiercely advocates for women's right to choose their own paths in life. Tasked with protecting the magical isle and tending to the needs of its residents, she carefully trains Marigold to take over her responsibilities before passing away peacefully.

August is Marigold's childhood friend who reconnects with her after years apart. He is bright, dangerously curious, and approaches life with a fearless desire for adventure and romance. He believes deeply in love, arguing that it is always worth the risk of heartbreak, and seeks Marigold's magical assistance to navigate his own romantic troubles.

Versa is a powerful Ash Witch who seeks to consume the magic of Innisfree to achieve immortality. She is responsible for placing the curse on the Honey Witch family line in an attempt to eliminate any opposition to her goals. She utilizes dark ash magic and serves as the primary threat to the health of the isle and its guardians.

Raina is Marigold's mother, a woman who long ago chose to forsake her magical heritage in favor of a traditional life of love and family. She attempts to shield Marigold from the magical world, believing that a safe, conventional marriage in Bardshire is the best path for her daughter.

Mr. Benny is a kind, dependable farmer who owns the property across the lake from Innisfree. He serves as a loyal companion and assistant to Althea, helping her gather magical ingredients and transporting her in his carriage. He extends his supportive nature to Marigold as she adapts to life on the isle and grieves her grandmother.

Aster is Marigold's younger sister who comfortably fits into the high-society life of Bardshire. Unlike Marigold, she embraces courtship rituals and societal expectations, eagerly pursuing traditional milestones like engagement and marriage.

Frankie is Marigold's younger brother, a sensitive young man navigating the social pressures of Bardshire. He longs for genuine connection and feels occasionally isolated, prompting him to reach out to his estranged sister for emotional support.

Lord Claude is Marigold's father and a highly celebrated artist in Bardshire. He provides a comfortable, wealthy life for his family and demonstrates a warm, welcoming demeanor toward Marigold and her guests when they visit.

George is Marigold's significantly older ex-lover. He is an artist who previously used his age and status to attempt to mold Marigold into an obedient partner, leaving her with emotional scars and a deep skepticism regarding marriage.

Edmund is a young poet and August's romantic partner early in the story. He reminds Marigold of the stuffy artists she left behind in Bardshire, and his presence earns Lottie's immediate and bitter disapproval.

Lunasia is a landvættir, a spirit guardian of nature that appears in the form of a giant, glowing blue butterfly. She shares a quiet bond with Marigold, accepting offerings of honey cake and signaling changes in the magical atmosphere.

Chesha is a landvættir taking the form of a cat on the isle of Innisfree. As a guardian spirit, she reflects the magical health of the land and reacts instinctually to the presence of ash magic.

Madame Genevieve is the town modiste in Bardshire. She is highly observant and notoriously gossipy, posing a social threat when she discovers information that violates the town's strict societal rules.

Mr. Woodrake is a painter in Bardshire who successfully courts Aster Claude, fitting perfectly into the traditional high-society lifestyle expected by the Claude family.

Mr. Notley is a handsome and charming gentleman who serves as one of Raina Claude's attempts to set Marigold up. He is polite but represents the stifling, conventional life Marigold wishes to escape.

Caoimhe is a pregnant woman from Lennox who faces life-threatening pain. She travels to Innisfree so Althea can use honey magic to save her life and the life of her unborn child.

Ronan is Caoimhe's husband, deeply distressed by the potential loss of his love. He travels with his wife to Innisfree and distracts himself by speaking with Marigold while Althea works her magic inside.