Season 1 had the cassette tapes, but Season 2 of 13 Reasons Why was all about the polaroids. Throughout the new season, troubled teen detective Clay Jensen receives a number of damning polaroid pictures that lead him to investigate a secret culture of sexual abuse among the high school's baseball team, and the big question for much of the season is who is sending Clay these photos. Towards the end, the mystery of who sent the polaroids in 13 Reasons Why Season 2 was finally solved, and it was a totally unexpected person.
Spoiler alert: Do not continue reading if you haven't finished 13 Reasons Why Season 2 yet and want to get through it without spoilers. The mysterious polaroids that keep popping up around Clay become the driving force in his quest to get justice for Hannah Baker's death. Each photo shows members of the Liberty High School baseball team taking advantage of unconscious girls, and includes a cryptic message written on the back. Over time, these polaroids lead Clay to the Clubhouse — a hidden shed behind the baseball field where all the shots took place — and he finds an entire box full of the shocking photos. It is clear that whoever has been sending these photos to Clay knew about the Clubhouse and wanted to expose the baseball team, but who could that be?
The answer finally came towards the end of Season 2, when Zach Dempsey surprisingly admitted that he was the person giving Clay the polaroids all along. Honestly, I was pretty sure that it was going to be the baseball-playing Season 2 newbie Scott Reed, whose only role in the show appears to be saying that he is a jock who doesn't sexual assault people. Perhaps the 13 Reasons Why team decided to include Scott in the new season so that viewers would suspect him as the polaroid sender, because after him, the only other decent person who seems to be on this baseball team is Zach.
Throughout Season 2, we learn a whole lot more about Zach's past and his personal struggles. In the first season, all we really knew was that Hannah included him on her tapes because he stole the complimentary noted that other students were writing for her, making her feel even more dejected and alone than ever. However, the second season included the bombshell that Zach and Hannah had actually secretly dated the whole summer before her death. When school started back up again, though, Zach refused to tell any of his friends about Hannah, and they broke up because of it.
Zach definitely felt a ton of guilt about what happened to Hannah, which was probably one of the reasons that he became so devoted to helping Alex after his suicide attempt. In the new season, much of Zach's time is spent helping Alex recover from his near-death experience, creating a strong friendship between the two. But the same thing that drove him and Hannah apart also creates tension between Zach and Alex: Zach continues to hang out with Bryce and the rest of the baseball team, who ridicule Alex, and Zach remains quiet or downplays his friendship with Alex.
Finally, Zach gets the courage to stop remaining quiet. After admitting his relationship with Hannah in court and having the baseball coach ask him to stick by his teammates, Zach quits the team and tells Clay that he is the one who has been sending the polaroids, hoping to expose the violent culture within the circle of jocks. It was a totally redemptive moment for Zach, who was presented as a bad guy in the first season, but became one of the most likable characters in the new run of episodes.