Gwendoline is the young protagonist. She is a girl of mixed heritage, born to a Japanese mother and an English father, George Russell, the Viscount of Marble. At the start of the story, she is approximately five years old. Her life is irrevocably changed when her mother dies in a car accident while they are traveling to England to reunite with her father, whom Gwendoline has never truly known. Following this tragedy, she is brought to live in her father's grand manor in England.

Gwendione's personality is marked by resilience and an enduring cheerfulness. Despite the hardships she faces, she displays remarkable courage and a strong will, often described as an energetic and spirited child. While she can be lively and at times mischievous, she is also deeply sensitive and sincere, often demonstrating a naivety that comes from her youth and good heart. For instance, even when her grandfather rejects her because of her "impure blood," she still feels love for him when he shows a rare moment of kindness. Her primary motivation is to honor the promise she made to her late mother: to grow up to be a strong, elegant, and true lady. This goal gives her the strength to persevere through numerous adversities.

In the story, Gwendoline's role is to navigate a hostile and complex world that is often cruel to her. Her arrival at the manor is met with rejection by her half-sister, Annie, who initially sees her as a rival for their father's attention. The primary source of conflict comes from the Baroness de Wibbery, a manipulative and greedy woman who seeks to marry Gwendoline's father for his title. The Baroness, with the support of Gwendoline's grandfather, brings her own cruel and spoiled children, Mary and Antoine, who frequently cause trouble for which Gwendoline is unjustly punished. Throughout these trials, Gwendoline remains a figure of perseverance, refusing to be defeated by their schemes.

Her key relationships provide her with crucial support. She finds steadfast friends in her neighbors, Arthur and Edward de Brighton, who immediately accept and defend her. Her bond with her half-sister Annie eventually softens from coldness to genuine sisterly love. Later in the series, Gwendoline goes to live with her aunt, who educates her in the ways of becoming a proper lady. In this new environment, she faces further social challenges, including jealousy from other girls like Vivianne at her new school.

Throughout her journey, Gwendoline's character develops as she learns to navigate the strictures of high society while holding onto her innate kindness and strength. She is not portrayed as having any magical or superhuman abilities; her notable strengths are her emotional fortitude, her unwavering optimism, and her ability to remain sincere and forgiving in the face of mistreatment, which ultimately helps her win over many of those who initially opposed her.