Charming and unobtrusive, Cynthia is the youngest of the Brisby children. Apparently the most innocent and naïve of the bunch, she enjoys Auntie Shrew's visits and could be said to be the least trouble-prone of the four Brisby bunch. With a tendency to be overlooked, she is rather fidgety - a trait which Auntie Shrew maintains is much like her mother's.
Quote: "Oh the poor turkey fell down!"
Origins of the character: In Robert C. O'Brien's book "Mrs. Frisby And The Rats Of NIMH", Cynthia is a bit more talkative (and better with words) than in the movie. She is described as "a slim, pretty girl-mouse, light haired and, in fact, light-headed as well, and over-fond of dancing."
In the animated sequel: In this movie she, like her older sister Teresa, has even a smaller part to play than she did in the first movie. She's a few years older, and appears to have put on some weight too, as seen in this screen shot of three of the Brisby children (L-R: Teresa, Cynthia and Martin):