Well, you should know what a protagonist is, it's commonly known as the "good guy" or the main character in a story. If the setting revolves around the protagonist's lifestyle and choices, then the setting can be changed or deformed. If the protagonist were to react to a certain setting with a negative reaction, then the entire plot can shift, including the characters. For example, if a story about a stranded sailor who became stuck on an island progressed from the sailor being affraid and petrified, and turned into the sailor adapting to his environment and learning how to survive, that would be a major setting change not only for the plot, but also for the protagonist. The identity of a protagonist can change significantly through the setting and vice versa! Hope this helps, this is my first answer to a question!