Allison's brief backstory revealed that she once worked as a bartender at O'Devlin's, a NYC sports bar. She was also engaged to Ryan Parisi, and one night while she was working, Allison was being hit on by Jeremy Harris and Craig Anderson. Ryan, who worked as a bouncer at the bar, ejected the pair, and it was after this that Ryan was shot in the back and killed instantly. Both Jeremy and Craig were questioned regarding Ryan's murder, but no evidence connected them to the crime. Despite this, Allison not only blamed the boys for Ryan's death, she firmly believed that they killed him, leading to her becoming vengeful.
Allison's twisted plan began with seducing and luring Craig to the rooftop of an abandoned building, where she gave him wine laced with snake venom. Craig slowly succumbed to the poison and died in his car, and later on, the evil Allison did the same to Jeremy. Allison's plan to get away with her actions hit a snag when she was arrested on a drug possession charge, so she coerced fellow bartender Reuben Lewis into destroying evidence for her, which included forcing Jeremy's parents to do so under the threat of harming Jeremy.
Reuben's capture revealed his connection to Allison, and later on, Jo Danville visited Allison in prison and interrogated her. Allison boldly admitted to her actions, voicing her belief that Craig and Jeremy killed her fiancee, while also showing no remorse for what she had done--even after Jo informed her that a partial print on the gun revealed that neither of them killed Ryan. In fact, Allison even added that the boys could have enlisted another person to kill Ryan. After Jo pleads with Allison to reveal Jeremy's location, Allison does so, revealing that Jeremy was at a marine salvage yard. Jeremy was miraculously found alive, meaning that Allison was facing only one charge of murder and one charge of attempted murder, among other crimes.