- "I know you tried coming to my rescue, Zach. But we all know that's not why you're on this tape. So I've got one question before we continue. When you try rescuing someone and discover they can't be reached, why would you ever throw that back in their face?"
- ― Hannah Baker talking about Zach Dempsey
Zach Dempsey is the seventh reason why Hannah Baker killed herself. He used to be in Hannah's favorite class, (Peer Communications) with her before she died, and stole the hope that she desperately needed.
On the tapes, Hannah explained that on their date at Rosie's, Marcus Cooley tried to take advantage of her and called her a tease for not complying. After he left, Zach went to sit next to her, with intentions to land a date with the Hannah Baker, since he bet his friends that he could get a date with her easily. Hannah pretended not to notice him and Zach let her ignore him for a while. Finally, he asked her if she was okay and she nodded. Then he apologized for what happened before he arrived. When Hannah started to ignore him again, he went back to sit with his friends and they teased him about not landing a date with Hannah and didn't say anything against her. But as he thought moreand more about Hannah's silence, he began to take this personally. Although he didn't ask Hannah out, this was rejection enough, and he decided to get back at her for hurting his feelings, as well as his pride.
In Peer Communications, there is a system where students can speak positively to each other anonymously. Every student is given a paper bag to put in the back of the room, and students who wish to give them a compliment but don't want to say it in person could just write a note and slip it into their bag. Zach decided that taking Hannah's notes of encouragement evened out her "rejecting" him; this was his method of revenge. Hannah started to notice that her notes were missing, especially after she got a new haircut and knew that at least a few people in class she considered friends would compliment her on this new appearance. Over the weeks, she had no notes in her bag while other students in class were getting plenty. To find out what was going on, Hannah wrote herself a note and, the next day, it was gone from her bag. She watched her bag very carefully then and found Zach slipping a finger into her bag to check if there were any notes inside. She decided to write herself another note and set it up so that if he tried to steal it, the bag would fall to the floor. She caught him stealing her notes and was shocked that she was right about him.
After the bag fell, Zach exited the room, made eye contact with Hannah, and hurried down the hall, reading Hannah's note. Hannah shouted after him angrily with tears running down her face and ended up embarrassing herself in front of everyone for no apparent reason.