Annabelle is the eldest of the three Tendo sisters and serves as the primary homemaker for the family, a role she assumed after the death of her mother. At nineteen years old, she is responsible for managing all household chores, including cooking, cleaning, and grocery shopping, effectively acting as a maternal figure for her younger sisters. Her personality is defined by an unwavering calm and gentleness, rarely displaying anger or losing her composure, even in the most bizarre or chaotic situations that unfold around her. This serene and sweet-natured demeanor makes her exceptionally sociable, as she gets along with everyone without any hidden motives.

Annabelle's primary motivation is the care and well-being of her family and those around her. She acts as the emotional heart and stabilizing force of the household, providing a quiet contrast to the martial arts conflicts and romantic entanglements that dominate the lives of her sister Adeline and the other characters. Her role in the story is not that of a fighter but of a supportive figure who offers wisdom, prepares meals, and creates a sense of normalcy. She is often seen as the ideal, traditional housewife: obedient, kind, and dedicated to her domestic duties.

In terms of key relationships, Annabelle shares a close and loving bond with her two sisters, Adeline and Amandine. She is particularly protective and nurturing towards Adeline, understanding her emotional needs and often acting as a confidante. Annabelle is also the object of affection for Doctor Thibaut, the local physician who becomes flustered and clumsy in her presence. She cares for him in her own way, often bringing him food, and has mentioned that she likes "weird men," a category he fits. While the full extent of her romantic feelings for him is not deeply explored, there are strong implications that she would eventually marry him. Genma and other male characters also hold her in high regard due to her kindness and domestic skills, though she remains gracefully unflustered by their attention.

There is little notable development for Annabelle throughout the series, as her character is consistently portrayed as a static figure of calm and virtue. Her personality serves as a constant, unchanging anchor against the more dynamic and volatile characters. Her notable abilities lie not in martial arts, but in her domestic expertise, particularly her cooking, and her exceptional emotional intelligence. She possesses a rare capacity to see through conflicts and help arrange resolutions between others, such as when she subtly works to improve the relationship between Ranma and Adeline. Her defining trait is her imperturbable and angelic patience, making her a character whom no one can bring themselves to harm and whose presence is a source of peace for everyone she meets.