She grew up in Lakewood along with her childhood friend Brandon James. During their childhood, they would write notes to each other and hide them for each other to find. Her family called Maggie "Daisy" but the only one besides her family who knew of this was Brandon. When Maggie started maturing into her teenage years she met Kevin, who became her boyfriend and husband. However, Brandon never liked him and felt she deserved better due to Maggie confiding her relationship issues with him.
One night, Brandon went to a dance where Maggie was attending and was assaulted by high school students, which caused Brandon to snap.
At some point in the past Maggie and Brandon had hooked up together which Kevin found out. Brandon had enough and just snap and killed 5 students in one night on October 31,1994. Her future husband Kevin Duval somehow managed to survive the rampant killing spree. Maggie managed to meet Brandon at Wren Lake to talk to him, but she was unaware when her father called the police on this.
According to Maggie, when she met him he seemed scared and she believed he did not commit the murders. Brandon gave her a carved necklace he made for her before saying all he ever wanted was for them to be together, but the cops ambushed and shot him, and he fell into the lake, where he was presumed dead.
However, Maggie later discovered Brandon was still alive, and, with her friend Miguel, took care of Brandon before letting him disappear. Her father covered up her name in the reports and media because she was 16 and a minor, allowing Maggie to bury her past as Daisy.
Years later, Maggie and Kevin got married, they had at least one daughter, Emma. The marriage between the two ended badly due to Kevin getting drunk too often. One day, Kevin tired to take Emma somewhere but Maggie protested, Kevin got so angry that he attacked Maggie and fraxtured her jaw. Horrified at what he had done, Kevin left town leaving behind his daughter.
In Season 1, Piper returned to Lakewood and started a killing spree, ultimately targeting Maggie and Emma in revenge for Brandon's death, and for being orphaned. In the end, Maggie was stabbed in the stomach but managed to survive.
In Season 2, Piper's former accomplice began a new killing spree. Maggie suspected Brandon James, having known he was still alive. She and Miguel work together to find out if he's alive and leave a note for him. Neither of them are attacked, and they soon learn that Brandon wasn't the killer, but Maggie finds the note bloodstained and pinned with a knife.
Despite all of this, Maggie continuously concocts ways to further Emma's dependence and loyalty to her, by regularly tending to her as a loving mother; making her favorite meals, gifting her with paint and other luxuries to keep her occupied within the tower, as well as posing as a protector in the overly dangerous world because of Brandon. Though all for a deeply selfish reason, and at the expense of Emma's happiness and dreams of seeing the outside world.