One Dark Window

Why these tropes fit

A cursed town and an ancient, morally gray spirit sharing the heroine's mind drive this gothic dark-romance quest. Secrets and hidden identities, including those of a mysterious highwayman, are wrapped in shadow and deception as the pair undertake a dangerous mission to cure Blunder's dark-magic blight. The bond between Elspeth and her enigmatic companion builds through undeniable, escalating tension while a darker threat slowly overtakes her from within.

Evidence from the source

• Curse: “An ancient, mercurial spirit is trapped inside Elspeth Spindle's head - she calls him the Nightmare.” source
• Hidden Identity: “When Elspeth meets a mysterious highwayman on the forest road, she is thrust into a world of shadow and deception.” source
• Quest: “they embark on a dangerous quest to cure the town of Blunder from the dark magic infecting it” source
• Strong Heroine: “Elspeth is forced to face her darkest secret yet: the Nightmare is slowly, darkly, taking over her mind.” source
• Dark Romance: “thrust into a world of shadow and deception.” source
• Morally Gray: “He protects her. He keeps her secrets. But nothing comes for free, especially magic.” source

Metadata source: Open Library. Quotes are used only to verify the tags.