In literature, a character foil is a literary technique in which two characters are used to contrast each other. A character foil typically has traits that differ from those of the protagonist or main character and often serves as an obstacle for them to overcome. The purpose of using this device is to draw attention to certain qualities within the protagonist by contrasting them with another set of characteristics. By doing so, authors can illustrate key themes and ideas more effectively than if they had only one central figure.
Character foils come in various forms, but all have similar goals: revealing different sides of characters' personalities or furthering their development through comparison and contrast. In many cases, a single secondary character acts as the primary foil for the protagonist throughout the story's duration; however, multiple foils may be used at once depending on how complex a particular narrative needs to be. Some examples include Dr Jekyll & Mr Hyde by Robert Louis Stevenson (1886), where Edward Hyde contrasts Henry Jekyll's reserved demeanor; Romeo & Juliet by William Shakespeare (1597), where Mercutio contrasts Romeo's romanticism; and To Kill A Mockingbird by Harper Lee (1960), wherein Bob Ewell stands against Atticus Finch's moral code.
When analyzing any work of literature, it is important to consider whether there are any characters acting as foils—whether intentionally employed or not—and what effect these figures have on our understanding of events and plot points in general. Such analysis helps readers better understand both individual characters' motivations while also bringing light on deeper underlying issues present within stories themselves—something that would otherwise remain hidden without such juxtapositions being made clear via characterization techniques like those provided by character foils.