Jervis Pendleton is a central figure in the anime adaptation, introduced as the wealthy and unconventional uncle of Julia Pendleton, Judy Abbott's roommate at the Lincoln Memorial High School. At the start of the series, he is twenty-seven years old, placing him approximately fourteen years older than the protagonist, Judy. He stands in stark contrast to the expectations of his social class, being neither stuffy nor preoccupied with status. Instead, Jervis is portrayed as an original, humble, and generous individual who treats others with genuine courtesy and respect, regardless of their position in society. He is known for his friendly, and sometimes goofy, sense of humor, which makes him approachable and endearing to those around him. His disdain for high society is well-known, and his preference for more meaningful interactions is a key aspect of his personality.

Jervis's role in the narrative is deeply intertwined with Judy's journey. He first meets Judy when his niece asks her to show him around the school. He is immediately drawn to her spirit, which contrasts sharply with the rigid social circles he typically avoids. As their relationship develops, he becomes a supportive figure, encouraging her writing and offering her a perspective on life different from her own. However, his most significant and secretive role is that of Judy's mysterious benefactor, whom she nicknames Daddy-Long-Legs after seeing his elongated shadow. As John Smith, he finances her education on the condition that she write him letters, which he reads with great personal interest. His motivations are complex; he is captivated by her writing and personality from her very first essay from the orphanage, and over time, this interest deepens into love. Using his position as Julia's uncle, he arranges to enter Judy's life in person, creating a situation where he can observe her and build a relationship with her directly, all while concealing his identity as her sponsor. This dual role as both her secret guardian and her romantic interest is the central secret that drives much of the story's tension.

Key relationships define Jervis's actions and development. His relationship with Judy is the primary focus, evolving from friendship to romance. His feelings for her lead to moments of jealousy, most notably when he orchestrates for Judy to spend a summer at his farm, effectively separating her from her friend Jimmie McBride, who is also in love with her. His family, particularly his sister-in-law, disapproves of his interest in an orphan and works to keep them apart. His feelings for Judy lead him to propose marriage, but she initially refuses, not out of a lack of love, but from a fear that her orphan status would one day make him regret the union. The rejection devastates Jervis, causing him to flee to Paris, where he falls dangerously ill with pneumonia. This crisis becomes the catalyst for the story's resolution, as Judy is called to his bedside by his secretary, Walter Griggs. It is during this vulnerable moment that Jervis finally reveals the truth: he is John Smith, the Daddy-Long-Legs who changed her life.

Throughout the series, Jervis undergoes significant development as he navigates the consequences of his dual identity. While he is presented as a kind and well-meaning man, his actions reveal a manipulative streak. He uses his wealth and influence to control Judy's environment, such as discouraging her from accepting a scholarship to ensure her continued dependence on him. His secret identity allows him an immense amount of power over Judy, a fact that is often met with discomfort by viewers who note the imbalance in their relationship, given her youth and his authority as her guardian. Judy, upon learning the truth, is shocked but ultimately forgives him, and her care for him during his illness solidifies their bond. After he recovers, they are able to move past the deception. The story concludes four years later with Judy having finished college and marrying Jervis, finally uniting her love with her benefactor. His notable abilities lie not in physical prowess but in his financial influence, his patient manipulation of those around him, and his genuine, if flawed, capacity for deep affection.