The middle Fossil sister with a distinct Russian heritage, more interested in mechanical pursuits than the performing arts. She values practical, hands-on activities and dreams of a future in aviation.

The youngest Fossil sister, characterized by her red hair and exceptional talent in ballet. Her passion for dance leads her to special training opportunities and a resolute focus on her future in the discipline.

The Fossil sisters' adoptive mother and their great uncle Matthew's great niece, responsible for their upbringing. Known as Garnie, she manages household challenges and supports the sisters in pursuing their interests.

The loyal and stern nurse who assists Sylvia in raising the Fossil sisters, drawing on her nurturing experience. She emphasizes care and discipline, guiding the girls from their early years through adolescence.

A boarder in the Fossil sisters' home who shares a special bond with Petrova over their interest in mechanics and aviation. His support extends to providing transportation and aid to the sisters.

A retired professor and boarder who becomes an important figure in the Fossil sisters' education, offering instruction and assistance in academic and theatrical pursuits.

The head of the performing arts academy who personally mentors Posy in ballet, drawing from her own illustrious career in dance. She is a pivotal figure in nurturing Posy's talent.

Sylvia’s great uncle who adopts the Fossil sisters and plays a vital role in their early lives despite his frequent absences due to voyages. His adventurous spirit influences his relationship with the girls.