Sidonie Laborde is a fictional character from the novel "The Elegance of the Hedgehog," written by Muriel Barbery. She is a young girl who lives in a Parisian apartment building and is known for her intelligence and curiosity about the world around her. In the story, Sidonie forms a bond with Renée Michel, the building's concierge, and Paloma Josse, a precocious twelve-year-old girl. Her character represents the innocence and perspective of youth, contrasting with the complexities of adult life explored in the novel.