Martha Moppet functions as the maternal figure within the Moppet family. She is George Moppet's wife and Lulu Moppet's mother, consistently portrayed with a patient parenting style that contrasts with her husband's approach to discipline and household management. She demonstrates skill in domestic activities, with multiple sources highlighting her proficiency as a cook, making this culinary ability a recurring aspect of her household presence. Her interactions with George frequently involve uncovering his attempts to avoid responsibilities, such as bribing Lulu to perform his duties. Within family narratives, Martha occasionally appears alongside George in fictional stories Lulu creates for Alvin Jones, maintaining her established family role without expanding into new dimensions.