Thea Stilton is Geronimo's younger sister and special correspondent for The Rodent's Gazette. Thea taught a journalism class at Mouseford Academy to five mice, Nicky, Colette, Violet, Paulina, and Pamela, who would name their group after her as the Thea Sisters and chronicle adventures of their own in the Thea Stilton series. She was also adopted by the Stilton family when she was young with her biological brother, Geronimo Stilton.