Mary Gannon was born in Twinbrook to Charles and Jill Colebank. She was very playful and nurturing, and showed a gift for cooking since she was a child. A little while after she grew up to be a child, her parents had another baby, Craig. She got along very well with her younger brother and took care of him when her parents went out.
When she turned into a teen, her family went on a vacation to Riverview, where she met her future husband, John. They quickly fell in love and stayed together during the whole summer, but had to go their separate ways when her family returned to Twinbrook. She felt sad for being away from her boyfriend, but she stayed in touch with him until her prom, when he stopped calling. She fell into a depression and wanted to stay at home on prom night, but then John appeared at her doorstep and took her to the party.
After graduating from High School, Mary moved to Riverview, where she rented a small house near the Brokes. She started a career in the Culinary career and got engaged to John. She then got married in a big ceremony in a park near the river.
She moved in with him and had a healthy and happy marriage - they engaged in several activities together, such as having picnics, cycling, fishing, swimming, among others. However, their relationship got strained when she got pregnant.
During her pregnancy, John took care of Mary's every need and, nine months later, their son was born. Mary had a nurturing approach in raising Jake, but John had a different manner in doing that task. When Jake was a child, she got him a Siberian Husky, Buddy, whom John didn't like much, but allowed the dog in the Manor.
When Jake was almost a teen, Mary's mother died and her father and her brother moved in with the Gannons and the two of them didn't help in the conflict - each one of the four tried to raise Jake in a different way.
One day, one of John and Mary's usual fights was worse than the usual and John threw a vase into the wall. Mary realized that their fights weren't helping Jake and, after marriage counseling, they decided to move to Bridgeport after she quit her job.
Their life in Bridgeport was calmer, possibly because Jake's preferences and ideas were almost established, and their marriage was starting to get better. However, the family's happiness was short-lived. On Jake's 15th birthday, they went to the Prosper Room to celebrate and on their way out, they faced a mysterious man trying to assault them. John tried to fight the criminal, but he killed him. Then, while trying to protect her son, Mary died at gunpoint as well.