Aunt Marge is one of two retired schoolteachers who care for a young girl named Rose, rescued from a sinking island by the vampire Lestat. He adopts Rose and needs dependable mortals to raise her and love her. He chooses Marge and her roommate, Julie. Lestat constantly sends them money and gifts so that they will never need to worry. After Rose gets embroiled with a corrupt judge and school, Lestat sends Louis to escort her, Aunt Marge, and Aunt Julie to New York, where they live in opulence.
Aunt Marge is mentioned in Prince Lestat (2014). For more perspectives on her character, read the Alphabettery entries Aunt Julie, Lestat de Lioncourt, Louis de Pointe du Lac, and Rose.