Like her book counterpart, Courtney also became friends with fellow classmate Hannah Baker, and eventually came to help her in a plan to deal with classmate Tyler Down, who was taking pictures of Hannah through her bedroom window. In the book, Courtney and Hannah's plan was to allow Tyler to photograph Courtney massaging Hannah in an alluring way. The Netflix adaptation has their plan being along the same lines, but the plan goes awry when the girls become drunk and begin kissing.
After realizing Tyler had gotten a picture of the act (though Courtney's face was left obscured), Courtney grew fearful of being exposed as a lesbian and decided to spread sexual rumors about Hannah, doing so to draw the student body's attention away from Tyler's photograph. Courtney's callous act of self-preservation took a toll on the already emotionally damaged Hannah, with Hannah ultimately committing suicide as a result of a series of actions she documented on cassette tapes to be distributed to Courtney (amongst others) by her friend, Tony Padilla.
The series (like the book) centers around protagonist Clay Jensen listening to the tapes, eventually coming to learn Courtney's actions against Hannah when listening to her tape. Clay confrontned Courtney while the two visited Hannah's grave marker, with Clay blasting Courtney for throwing Hannah under the bus to protect her own secret. While she initially refused to admit that she was gay, Courtney ultimately confessed to being a lesbian, while revealing that she had witnessed the homophobia her fathers faced for being a couple and feared what they would be accused of if she came out. Courtney later on joined several other students listed in Hannah's tapes in the goal of keeping Clay quiet about the tapes, even approving of Marcus Cole's act of planting drugs on Clay to destroy his credibility.
Courtney's callousness culminated in her agreeing to cover up the actions of Bryce Walker, who was on the tapes for having raped Hannah, who had also witnessed him raping fellow student Jessica Davis, doing so to keep the rest of the tapes from being uncovered. But ultimately, in Season 1's final episode, the tapes were given to Hannah's parents Olivia and Andrew and Tyler later talked about the tapes in his deposition hearing regarding Hannah's death, with Courtney's final scene of the season showing her being confronted about the tapes, effectively outing her sexuality.
Season 2 & Redemption
Courtney later re-appeared in the second season of 13 Reasons Why, which centered around the trial between Hannah's parents and Liberty High for their role in Hannah's death. Initially, Courtney continued to try and hide her sexuality when taking the stand, claiming her kiss with Hannah was a meaningless thing between girls. But eventually, as the school's attorney Sonya Struhl began to argue that Hannah had bullied Courtney and taken advantage of her that night, Courtney finally told the truth, confessing to being gay and initiating the kiss with Hannah; even revealing how Hannah had only kissed her back to make up for inadvertedly rejecting the crush Courtney had for her. Courtney later continued to express her remorse to Jessica Davis later on, with Courtney expressing deep regret for having hurt Hannah before helping her posthumously.
Courtney additionally began to pull after from Marcus as he continued to try and cover up his actions and stood by Jessica (along with her other friends) when she finally gained the courage to file charges against Bryce for raping her. Courtney was also present for Hannah's memorial service and later attended the school's Spring Fling with her girlfriend Tamika, having now gained the courage to be open about being a lesbian. She also joined in comforting Clay when a song he danced with Hannah to ("The Night We Met" by Lord Huron) played.
Appearance & Personality
Throughout the season, Courtney was shown to dress in semi-formal and typically feminine clothing, likely a hint to the fact that she was covering up her status as a lesbian. Courtney was also shown to be heavily involved in school activities and be a part of a large social circle, clearly placing value in her reputation and social status. Whilel Courtney appeared to genuinely like Hannah (possibly even in a romantic sense, given how they kiss), she is still willing to betray Hannah's friendship and throw her under the bus via rumors to cover her sexuality. After Hannah's suicide, while she has a bout of remorse during her confrontation with Clay at Hannah's grave, she is still willing to align with Marcus Cole's attempts to silence Clay to cover her secret, even to the extent of hiding Bryce's acts of rape against Hannah and Jessica (though she notably has little to no physical involvement in the cover-up). Initially, Courtney was shown as a self-centered person, willing to do anything to protect her secret, no matter who was hurt in the process.
However, in Season 2, as Courtney works to redeem herself for betraying Hannah, her remorseful and sympathetic side is shown more clearly. As shown through her testimony during the trial against Liberty High, Courtney's actions against Hannah were motivated not just out of self-preservation, but out of fear of the toxic bullying culture in her school. Her statements to Jessica Davis solidify Courtney's remorse for betraying Hannah and not standing up for her out of fear, showing that her callous actions were motivated solely by fear and desperation. It was also suggested in the second season's finale that Courtney (like Hannah and Jessica) was a victim of sexual assault at Libery, specifically related to her sexuality, likely contributing to her actions throughout the series.