Brimstone is situated within the dark fantasy romance genre, often called “romantasy,” which has seen a significant surge in popularity, largely propelled by social media platforms like TikTok, as noted in SuperSummary’s A Reader’s Guide to BookTok. The popularity of dark romantasy is often attributed to its combination of epic fantasy worldbuilding with emotionally intense romantic storylines, allowing readers to engage with both large-scale political conflicts and intimate character relationships at the same time. This genre is defined by conventions such as complex magical systems, political intrigue between supernatural factions, and morally gray characters. Brimstone employs these elements through its world of Fae courts and vampire politics, where Saeris must navigate a hostile environment as the new queen. Dark romantasy in particular often emphasizes violent or dangerous settings, enemies-to-lovers dynamics, and relationships shaped by power imbalances, which are all present in Saeris and Kingfisher’s relationship and in the political structure of the Blood Court.

A key trope central to the novel is that of “fated mates,” an unbreakable, predestined bond between two characters. This is a hallmark of influential romantasy series like Sarah J. Maas’s A Court of Thorns and Roses, where the romance is characterized by intense passion, possessiveness, and a shared destiny that transcends political conflict. The fated mates trope typically involves a magical or divine bond that ties two characters together emotionally and physically, often granting them enhanced abilities when they work together and making their relationship politically significant as well as personally meaningful. This trope is evident in Brimstone’s portrayal of Saeris’s connection to Kingfisher, who tells her, “There isn’t much I wouldn’t sacrifice to make you happy, Osha” (16). This all-consuming bond provides a powerful emotional anchor amidst the brutal warfare and political maneuvering of the Fae and vampire courts, aligning the novel with the core expectations of the dark fantasy romance genre and its dedicated readership.