Maria Bertram is not depicted as a sympathetic character. She does not have her father's discipline nor her brother Edmund's compassion, especially for her cousin, Fanny Price. She is condescending and gives Fanny the toys of the least value to her. She would also mock Fanny for her lack of knowledge and reports on Fanny's apparent deficiencies to her Aunt Norris. When she grows to adulthood, her attitude towards Fanny is not improved.
When Maria's father, Sir Thomas Bertram, goes to Antigua to improve the profits from his plantations, Maria, believing herself to have no prospects and being at the age to marry, becomes engaged to a young man named Mr. Rushworth at the prompting of Aunt Norris. Although Mr. Rushworth was not very intelligent or handsome, Maria agreed to his proposal of marriage for his estate of 700 acres was worth about 12,000 pounds per annum, a very large sum at the time.
Immediately after Maria's engagement to Mr. Rushworth, a young man named Henry Crawford comes to the neighbourhood with his sister, Mary. Because Maria has no real affection for Mr. Rushworth, she does not scruple to flirt with Henry. Henry Crawford also favours her over her unattached younger sister Julia because of her engagement although Julia, too, is attracted to Crawford. This puts Maria and her sister in competition with one another. When Maria's father returns from his journey to Antigua, Maria is married Mr. Rushworth, due to her belief that Henry had only used her for his own amusement and with the approval of Mr Rushworth by her parents and aunt. She goes to Brighton on her honeymoon and invites Julia.
Maria goes to London with her husband, where she encounters Henry at a party. Her infatuation for him was quickly renewed, and the two of them soon elope, bringing shame to her family and disgrace on her. Henry does not marry Maria, and Mr. Rushworth divorces her for adultery. She moves to "another country" with her Aunt Norris, who has always favoured her of all of her nieces.