Who is Miss Marguerite Parsons from The Man Who Listens to Horses and what is their importance?

Miss Marguerite Parsons is a central figure in Monty's early life. She is a kind tutor with a 1940s hairstyle and deep brown eyes. He describes her as a "woman of character." She is Monty's babysitter and also his teacher. Monty loves and respects Marguerite. She stays working with Monty until he is 14. On many occasions, Monty finds that Miss Marguerite Parsons is the only person who is sympathetic to him.