The main characters in the book The Face on the Milk Carton are as follow:
Janie is a red-headed teen who sees her picture of herself when she was around 3-4 years old on a milk carton. It indicates that she had been kidnapped. She struggles internally as she tries to decide how to handle the situation. She loves her parents and is very confused.
Reeve is the boy next door. He is the youngest teen in his family. He is also the least smart out of his siblings which bothers him. He likes Janie and becomes her boyfriend. He also tries to help her to decide what to do about her problem.
Sarah-Charlotte is Janie's friend whom she hangs around with at school and socially. Sarah's family are friends with Janie's parents and tailgate with them. Sarah also feeds into Janie's relationship with Reeve.
Mr. and Mrs. Johnson are the people who have raised Janie and who she has believed were her parents. She later learns from them that they are her grandparents. In he end they are no relative relationship, but have raised her believing she had been their daughter's child.