Kate Thorvald is Harriet and Nels Olesons' niece. When she came to visit them in Walnut Grove she had an accident and got injured when leaving the stagecoach. To make sure that she was all right, Charles Ingalls carried her over to Doctor Baker's office. This was the first time that they met.
After being together for a time Doctor Baker proceeded to court Kate, until he realized he was much too old for her. She stayed in Walnut Grove for a while but eventually returned home.
Behind the scenes
Kate was portrayed by actress Anne Archer.