Setting

I think that setting defines the entire play or novel. Situational factors from time periods, nature, and even the actual placement of the characters determine how the play works out. In Pride and Prejudice, if Liz was in a different time period or in somewhere else in the world, the play probably wouldn't have the same plot and Liz, as a character, would be a different person. Similarly, in Hamlet, if Hamlet wasn't royalty, the plot and the characters would be influenced very different.