Fiona is Sam's greedy stepmother and the main antagonist. She got married to Sam's lovable but foolish father Hal Montgomery. All went well for Sam until the Northridge Earthquake struck the valley and killed Hal. For seven years, Fiona got all Hal's belongings. Fiona really enjoys bullying, abusing and tormenting Sam, it makes her feel very good. She is a vain and obese woman who is selfish, greedy, snobbish, arrogant, pompous, conceited and grandiose. She tries to make Sam stay at the diner by duping her with a fake rejected letter from Princeton. When the twins blame Sam for vandalism, which covered an inspiring quote, Sam finally says "No!" to Fiona, quits her job and leaves her stepfamily, finally fed up with them treating her like Cinderella. When Sam found Hal's will, the house, the diner, and everything went to Sam. Fiona had signed the will as a witness and was arrested after being chased by the deputy police in the front yard of Sam's house. Then Fiona made a deal with the District Attorney. She was working off her debt to society at Hal's Diner.
In her wedding form: she wears ivory suit, with ivory dress skirt, white gloves, and her wedding white hat veil.
She is portrayed by Jennifer Coolidge