Literary device designed to illustrate or reveal information, traits, values, or motivations of one character through the comparison and contrast of another character
Ex: "in Frankenstein, Mary Shelley utilizes the creature as a foil for his creator, Victor Frankenstein. Frankenstein isolates himself from others to pursue his obsession with creating a living being and then he abandons his creation and all responsibility. The creature Frankenstein creates searches for companionship and connection with others as a result of his creator's rejection and abandonment, leading to violence and destruction."