Dahlia Ventura arrived in Oakdale in late 2001 and immediately insinuated herself into the lives of Katie and Simon Frasier. Upon meeting Katie, Dahlia was instantly drawn to her and offered her a golden opportunity: she'd make her an international star as an aerobics instructor. Though Simon was wary of Dahlia's motives in asking an unknown like Katie to make an aerobics video, Dahlia convinced Katie that her interest was genuine and they quickly signed a contract. Later, Dahlia confessed to Simon that she did have an ulterior motive for helping Katie: she wanted to steal Simon away! Though Simon scoffed and said that she could never come between him and his wife, Dahlia vowed that he would be hers. Dahlia spent the next few weeks planting doubts in Katie's mind about Simon's honesty. When Simon confronted her, she finally revealed her true motivation: she wasn't there to seduce him -- she wanted to make him pay for the death of her sister, Monique, one of Simon's many ex-wives. Believing that Simon murdered her sister, once she learned that he'd married her for her money, Dahlia was looking for revenge. After an argument with Simon, Dahlia suddenly disappeared. With blood found in her car, foul play was suspected and Simon became the prime suspect.
In the course of the next several weeks, events starting occurring that painted Simon as a murderer. A few attempts on Katie's life, the death of Dahlia's lawyer and even Simon himself conspired to poison Katie's mind against her husband. However, soon Katie realized that Simon could have killed her at any opportunity and her trust was restored. Then suddenly Dahlia showed up! Blaming Simon for her sister's death, Dahlia vowed to kill Simon but he startled her by grabbing the gun and when Katie walked in she inadvertently shot Simon! Claiming that Simon was trying to rape her, Dahlia told Katie that she and Simon conspired to murder her for her money. Unfortunately, by now Katie's trust in Simon was restored and she refused to believe Dahlia's lies and wrestled with her to get the gun. Luckily, Katie was able to get the gun and Dahlia was arrested. Later the Frasiers learned something unsettling: Dahlia murdered her sister!