Benedictine is a member of the mermaid race, a species characterized by the ability to possess two distinct forms, one male and one female. Benedictine initially appears in her female form but later takes on the male form known as Bennett after sustaining an injury, specifically a wound to the left eye, during a battle in the Catacombs. This duality is a core aspect of her identity as an aquatic being. Her role in the story is that of a unique artist and creative director within a musical sword-fighting band, an ensemble that coordinates performances and battle strategies. She is recognized as a water tribe member who serves as the director of an extermination squad.

Benedictine possesses extraordinary combat abilities, most notably the power to control and manipulate ice barriers with complete mastery. She employs this magic for both defensive purposes and to provide support for her companions in battle. Complementing her magical skills, she is also an exceptional archer, capable of performing precise long-distance shots and excelling in ranged combat.

Her personality is deeply influenced by the nature of her race, as mermaids are known to mirror the personalities of the individuals they form close relationships with. Initially, her relationship with the protagonist, Belle Lablac, was marked by a sense of incompatibility or distrust. However, a significant battle served as a turning point, dramatically altering their dynamic and bringing them closer together. This evolution in their relationship is a key part of her narrative. Her bond with a character named Gordon also serves as a major foundation for her personality, and his loss during a battle causes her a profound breakdown.

Benedictine's motivations are tied to her role in the band and her growing connection to Belle. Her abilities and brilliant performance in a decisive battle not only elevate her reputation as a creative director but also solidify her position among her allies. In a significant act demonstrating the depth of her connection to Belle, she transforms from her male form, Bennett, back into her female form, Benedictine, to calm and reassure Belle. She then heals Belle by linking their souls, a selfless act that results in her male form, Bennett, losing his eyesight. This event underscores her capacity for sacrifice and the profound bond she shares with Belle, whose personality she increasingly begins to mirror after the loss of Gordon.