Rilla is a tiny mousemaid with the most adorable, wide brown eyes which have captured the heart of many a Sister. However, behind her cute face, she is a mutinous mastermind full to the brim with mischief. She has tan fur, a white underbelly and commonly wears a pinafore, which usually doesn't last very long. She played a major role in the defeat of the Wolverine, and she was the first to read the message carved out on the walls of Redwall by the Lord of Autumn.
Her best friend is Seaspray the Otter, and her childhood 'archenemy' is Geod, who is, ironically, Seaspray's cousin.