Mary-Lou is shy and quiet it is not specified what she looks like in the first book she was scared of everything Gwen takes advantage of that to play tricks on her. By the time she and her form reach the Sixth Form, her confidence grows and can easily outwit Gwendoline.
During her years at Malory Towers she grows more determined and achieving. She is always eager to please people even though strong characters like Alicia get irritated when she tries to tidy their lockers or organise their things. During her early years at Malory Towers she was tricked by Gwendoline and made fun of by Alicia. At the end of First Form she began to make friends with Darrel and Sally. In the Second Form she was used by Daphne. Daphne used Mary-Lou by persuading her to do her French for her. Mary- Lou thought that Daphne liked her. Daphne was friends with Gwendoline but she began to like Mary-Lou. At the end of the book Daphne and Mary-Lou were best of friends. Her, Daphne, and Mavis always ended up making a three-some. She hates seeing people cry, and she becomes a nurse later on