Jennifer, who first appeared in the fifth season, is the younger sister of Michael Mancini. She was introduced as a playfully brash young woman who'd had an affair with the married Kyle McBride before they'd both moved to Los Angeles. She appeared to be happy to be all the way across the country from her parents in New Jersey after dropping out of Boston College.
Jennifer deliberately blew an interview with Amanda Woodward upon arriving in Los Angeles after Michael set it up for her. She did befriend Michael's wife, Megan Mancini After making amends with Kyle, she started fighting with Michael about his lack of support. She stormed out of the Beach House, despite Megan wanting her to stay.
Jennifer took a job at a strip bar in the valley as a waitress, but Megan informed Kyle of her whereabouts. By the time Kyle found her, her manager was demanding she take the place of one of the strippers. Kyle took her out of there and let her stay at his place while he went to the Dominican Republic to get a divorce.
She continued to taunt Amanda, but eventually, Kyle and Amanda got together as a couple. Jennifer decided to turn her focus to Craig Field, who had just lost his wife, Sydney Andrews, in an accident. She started a company with Craig and her brother Michael, which produced medical supplies, but it was a rocky business relationship.
After Dr. Mosley tried to warn her of a defective heart valve in Craig's plans, Jennifer tried to warn Craig, but he threatened to kill her if she told anyone. However, Brett Cooper had Craig removed from the project and repossessed his car. When Craig found out, he attacked Jennifer, but she was rescued by Billy Campbell.
Jennifer's major romantic interest of the show became Billy, whose wife, Samantha, was having an affair. After Billy's marriage ended, he and Jennifer concluded the series happily by moving to Rome together.