Frederica Vernon is a main character in Lady Susan. She is the daughter of Lady Susan Vernon, an immoral widow. Her mother hates her and wants her to marry someone she doesn't like. Frederica ends up being the victor, however, because of her morality.
Frederica is quiet and enjoys reading quite a bit. Her mother believes her to be a stupid girl, and takes out her anger on her. Her aunt, Catherine Vernon, sympathizes with her. Catherine recognizes that the girl is really quite pretty, even though she does not have her mother's great beauty.