The Jetty Journals has four main characters: Karen, the narrator, Sean, Sophie and Blair. They are all teenagers. Sean and Sophie are 15-16, Karen and Blair a bit older, but not much.

Karen comes from a middle-class family. Her mother is a nurse, her father works for anewspaper. She knows the Mornington Peninsula as a visitor, sometimes going there on family holidays or to stay at the holiday house of family friends.

Karen is the narrator, who starts a journal to try and help her track her mental health over time as events unfold. She starts out with little in the way of survival skills, but is smart, determined and survives against the odds.

Sean is a good-humored boy, fond of puns and lame jokes, quite often happy despite the difficult circumstances they are in. His parents were a bit absent, and in fact he was staying with his grandparents because he had been sick and his parents were too busy. He is a loyal friend to Karen.

Sophie lives on the peninsula, and knows her way round, and her knowledge saves them many times. She was close to her parents, who perhaps dominated her life. She is serious, and although physically small, surprisingly tough.

Blair is bitter, having been through an awful time when the plague broke. We don't get the full story about Blair...for good reason, he hides a secret. His bitterness takes the form of vengeance on the ferals, and occasionally leads to exposing the group to terrible risks. He also lived on the peninsula, but didn't really fit in, having moved to the coast from the country. His father was the local policeman.