Jessica first appears in American Pie as Vicky's sexually experienced friend. Finch pays her to tell all the girls in school of his sexual prowess, hoping it would increase his chances of having a date before the upcoming prom. She also helps Vicky and Kevin with their relationship: she teaches Vicky about sex, while she tells Kevin that he needs to make Vicky feel special by giving her an orgasm.
In American Pie 2, she has a much smaller role. She appears with Vicky at Kevin and his friends beach house party. In this film it is shown that she has a frenemy/crush on Stifler as it shows on two occasions: at the party when the group were asking how many people they slept with, Stifler asks her how many girls she slept with and she replies "Wouldn't you like to know?" and he says "Hell yeah", they both then laugh for bit which shows a sign of them flirting. The second case is when Nadia and Sherman are about to have sex with each other and Stifler and Jessica both are shocked and look at each other for a bit (almost like if they were about to kiss) and walk away from each other.
In American Wedding, she does not appear like Vicky and Heather.
In American Reunion, Jessica has a cameo appearance, where it is revealed that she is now a lesbian and has a girlfriend. She gets Kevin to apologize and make up with Vicky, who is upset and disgusted that Kevin could think that she would sink so low when he accuses her for having sex with him when he is married. Stifler walks past and meets Jessica and her girlfriend and he says "I knew it".
Relationship with Vicky and Kevin Edit
In American Pie, Jessica acts as the voice of reasoning in Vicky and Kevin's relationship, usually guiding and helping them throughout the film.
In American Pie 2, Kevin tells Vicky that he slept with 3 girls and Jessica divides that number and tells Vicky that he most likely slept with only one or even no girls.