Olive Penderghast (Emma Stone) is the main character in Easy A. She begins the movie as a relatively unknown junior in a high school in southern California, showing above average academic ability in class.
Olive avoids a camping weekend with her best friend Rhiannon and her unusual parents by saying that she has a date with a fictitious guy at her brother's community college. After saying that she spent the whole weekend with the guy, Rhiannon infers that they slept together, and harangues Olive into confessing that this is true. Her initial anonymity disappears as Marianne, a conservative Christian, overhears their conversation and spreads the rumour that Olive lost her virginity.
Olive's transformation continues after helping out Brandon, a fellow student bullied for his homosexuality, to create a more socially acceptable persona for himself by pretending to sleep with him at a party. Brandon's popularity improves at school, while Olive gains notoriety for being promiscuous. Todd, Olive's crush and the high school's team mascot, saw her at the party and is sceptical about her notoriety after, in a game of 'seven minutes of heaven', Olive lied about them not kissing in order to save Todd's for not being ready for his first kiss.
A small number of boys privy to the truth about their tryst make her realise that she can profit from her new persona, as the boys' slim luck with girls causes them to offer Olive expensive gifts in exchange for improving their social standing. This includes Evan, the school fat boy, who was the first one to offer her a gift card to a store so they can both agree to spread the rumour that they went to third base together. This gives Evan the reputation of a stud later on, which is what he was hoping for. Olive agrees to go through with this because she feels sorry for Evan who also feels sorry for himself. However, Olive tells him that she would have gone out on a date with Evan, if he had been a gentleman about it. But its too late for that now.
Rhiannon disapproves of Olive's perceived behaviour, and in a public spat shouts that they're no longer friends.
Disaster strikes Olive as her new reputation causes Micah, Marianne's boyfriend, to lie about catching Chlamydia from her to stop himself from getting into trouble, and prevent Mrs Griffith, the school counsellor whom he slept with, from losing her job. Olive agrees to take the blame for Micah's chlamydia, while her parents become concerned with her recently more promiscuous-looking dress sense.
She noted that, in spite of her reputation, she hadn't been asked out on a real date at all, save a date offer from Anson, Rhiannon's crush. The date turns sour after Anson tries to pay Olive for sexual favours, and Todd, working at the restaurant of their date, gave her a lift home. Todd remembered where she lives, after carpooling almost ten years prior, and asks to kiss Olive. She declines, only because of the state of her current life.
After using her promiscuous reputation to gain the student body's attention in a pep rally, Olive confesses via webcast the truth of her exploits in order to save her worsening persona, and tells of her crush on Todd. Her prior confession to her English teacher causes the Griffiths' marriage to collapse, causing her great guilt. After the webcast, she kisses Todd outside the house and rides off with him on a lawnmower, ending the movie.
Olive is portrayed as a unique girl, being widely read for her age (seventeen, implied during a conversation with Marianne) and not fitting in with her more average peers.
However, Olive also portrays many typical teenage traits throughout the movie. These include singing 'Pocket Full of Sunshine' to herself all weekend, and craving attention in the form of her promiscuous persona.
She also appears to have a good-hearted nature, not feeling bad for lying about giving chlamydia to Micah but instead for breaking up the Griffiths' marriage.