Jennifer was from a small town in the United States called Devil's Kettle Minnesota. She was best friends with a girl named Anita "Needy" Lesnicki "since the sandbox." As they grew up together, Jennifer had become the popular girl, while Needy became the quieter one who Jennifer always kept around. One night when they were teenagers, they went out to a bar where a group called Low Shoulder, was performing. The lead singer, Nikolai Wolf was interested in Jennifer, only because he suspects she's a virgin. The group was actually worshipping Satan, looking for a virgin to sacrifice to Satan so they could cut a record deal. While the band performed the bar suddenly caught on fire, completely annihilating it and killing a few bar patrons. Jennifer and Needy barely escaped by going out the bathroom window.
Outside Jennifer and Needy found the band who seemed to have made out okay, despite Needy's pleas they took a seemingly shocked Jennifer into their van. Jennifer while in the van, saw occult books and various other satanic items which made her agitated. Once they arrived to their destination, Jennifer, unsuccessfully tried to escape. They forced her onto the ground and tied her up. Nikolai would then perform a chant before brutally stabbing Jennifer. But, unbeknownst to the band, Jennifer was not a virgin. Rather than her dying, she was possessed by a demon. It gave her superhuman strength and speed, as well levitation and immortality. There was one catch, she would have to forever feast on young male human (or teenage boys) flesh to maintain her eternal youth or else she would be vulnerable to decaying and death.
She had found her way to her friend Needy's house. Where she immediately went into the fridge in the kitchen and tried to eat chicken. But she vomited that out along with "black ferromagnetic fluid" which seemed almost alive for a short time before leaving Needy's home. She would later go out and slaughter at least 3 teenage boys (Ahmet, Jonas, and Colin) before she told Needy what happened to her and the grizzly murders she's committed.
Jennifer would later go after Needy's boyfriend Chip. She lies to him saying that Needy cheated on her with Colin. He almost believed her. After Jennifer's feminine wiles was lost on Chip, because of his love for Needy, Jennifer would attack the boy. She bit into his neck just as Needy arrived and fought with Jennifer. After a verbal exchange, Jennifer tried to kill Needy, but Chip stabbed Jennifer with a pool skimmer, wounding Jennifer and forcing her to flee. Jennifer escaped and headed back home as Chip died in Needy's arms. An enraged Needy would later go to Jennifer's home and break into her room, screaming "You killed my boyfriend!" and a fight to the death ensued. Needy would injure her but it had little effect. Jennifer would struggle with Needy biting on her on the shoulder as she does so. She even levitates them over her bed. Needy then took off Jennifer's BFF necklace (Needy has an identical one) which shocks Jennifer, giving Needy an opening for her to stab her in the heart with a box cutter, killing Jennifer.
After Jennifer's death, her mother comes in and catches Needy's hand on the box cutter after she stabbed Jennifer. Needy was arrested and sent to an asylum for the criminally insane. It was in prison that she discovered that the bite that Jennifer gave her, awarded her with much of the same powers as Jennifer. She would use the same powers to escape from the institution and would track down the band, Low Shoulder, who was responsible for Jennifer's demonic possession as well as the deaths it caused. She would avenge Jennifer and her victims by killing them with ironically, the same weapon they used to sacrifice Jennifer.