Jonathan Byers is a high school student that has an unusual talent for photography. He’s able to take very interesting photos that he develops himself with his 35-mm camera. He’s a very quiet character that doesn’t say much but is also smart and kind. He’s very protective of his younger brother Will and takes a lot of responsibility for looking after his family.
He’s a bit of an outcast at school where his peers bully him, but Nancy Wheeler and Jim Hopper are very kind to him. He’s very mature beyond his years and is very sensitive, which adds to his charm.
In the first episode, he takes some pictures at a party at Steve Harrington’s house, which his bully friends later rip up and break. This ends up being an important part of the story as it contains a silhouette of the Demogorgon. Later on, Jonathan and Nancy go into Hawkins National Laboratory to expose the Upside Down. They’re successful in maiming the creature, and then Nancy sacrifices herself to save everyone from it.
This led to a lot of theories and speculation online, including the infamous Mandela Theory. However, British GQ published an article saying that the Duffer brothers had gone back and edited an earlier scene to make Jonathan less of a perv. The original scene shows Jonathan sneaking up on Nancy and taking photos of her undressing, but it was changed to show him watching an about-to-be eaten Barb near a pool.