Miss Lemon serves as Hercule Poirot's personal secretary, providing indispensable efficiency through her exceptional organizational skills and meticulous attention to detail. She executes her role by managing correspondence, schedules, and operational logistics, directly enabling the smooth progression of Poirot's investigations.

Her personality combines stern professionalism with a dry sense of humor, evident in interactions, and she maintains a consistently efficient, no-nonsense demeanor. Underlying this lies a clear respect and admiration for Poirot, signifying personal loyalty within their professional relationship.

Her background, including upbringing, education, or life prior to Poirot, remains undisclosed. She exists primarily within the professional context of her secretarial role. The narrative introduces a familial connection via her great-niece, Maybelle West, who assists Poirot and Miss Marple; this serves as a link between the detectives without expanding on Miss Lemon's personal life or background. Her character development remains consistent, maintaining her established role and traits without significant evolution.

Her working dynamic with Poirot is defined by mutual professional respect. She provides essential administrative support crucial to his investigative successes, though she does not directly participate in solving crimes or analyzing evidence. Her involvement is confined to the main television episodes.