A major theory about Jackie's diary may have just been debunked by the Yellowjackets showrunners. The show follows a high school football team whose plane crash-lands in the Canadian wilderness. Taking place across two different timelines, Yellowjackets explores both the immediate aftermath of the crash and the lasting psychological impact on the survivors nearly two decades later. The series has drawn comparisons to both Lost and Lord of the Flies and has a compelling mystery at the core that is pure folk horror.
Production on Yellowjackets season 2 is due to begin in August, and the resolution of various plot threads has been teased by showrunners Ashley Lyle, Bart Nickerson, and Jonathon Lisco. One of these plot threads is the discrepancy in a diary entry that references movies released after Jackie's shocking death at the end of Yellowjackets season 1. There are a number of theories about Yellowjackets' diary discrepancy, but the most compelling theory may now have been debunked by Jonathon Lisco.
In an interview with Variety, Lisco addressed Jackie's diary, stating: "I don't want to say we will find out that Shauna wrote those entries necessarily, but, we will find out why they exist." Jackie's diary was first seen in Yellowjackets season 1, episode 6, during the annual visit to Jackie's parents by the grown-up Shauna and her husband, Jeff. Taking a moment away from the stiflingly awkward social interactions, Shauna finds herself in Jackie's teenage bedroom, untouched since the day of the crash. Picking up Jackie's diary, she reminisces about their friendship. The scene led to speculation that Shauna filled out the pages in the years after the crash, in an attempt to cope with her grief at Jackie's shocking death. While Jonathon Lisco's carefully worded answer doesn't completely debunk this theory, his shift in focus to why, rather than who, suggests a more supernatural element.
One of the strongest elements of Yellowjackets is the way in which it blurs the lines between what's real and what's supernatural. The show has never confirmed one way or the other as to whether the haunting visions and strange occurrences are the results of something supernatural or the feverish imaginings of the isolated and traumatized survivors. The events of Yellowjackets' season 1 finale have pushed things towards a more explicitly supernatural angle, from the human heart in Taissa's present-day basement to Jackie's haunting vision of those who have died. This delicate balance between the supernatural and the rational presents the possibility that Shauna didn't "necessarily" write the diary entries in question, and wrote them as a proxy for Jackie's ghost.
The ending of the 1996 storyline in Yellowjackets season 1 is devastating for Shauna and Jackie's friendship. After discovering that Jeff, then her boyfriend, was cheating on her with Shauna, Jackie attempts to oust her former friend from the group but is met by strong resistance from the others. Deciding to sleep outside, she freezes to death in the night, removing the opportunity for the two friends to ever reconcile. This is likely to weigh heavy on the young Shauna's mind throughout Yellowjackets season 2. In the heightened atmosphere of the survivors' isolation, it wouldn't be surprising if she conjured up a version of Jackie as both a coping mechanism and an attempt at reconciliation.
Yellowjackets season 1 has already confirmed that Shauna still experiences visions of Jackie decades after her death, which is either a manifestation of Shauna's guilt or something more supernatural. If the mysterious events of Yellowjackets are indeed supernatural, then the filled-out pages of the diary would be Jackie's words, physically transcribed by Shauna. It would mean that the socially excruciating visits to Jackie's parents and these impossible diary pages are penance for Shauna's betrayal, delivered by Jackie's vengeful ghost.