The examination of these two characters' bond takes up a big part of the film, but analyzing character foils is nothing new to cinema. A character foil is described as "a character who represents a sharp contrast with the protagonist and thus serves to stress and highlight the protagonist's distinctive temperament," and plenty of films have them. We decided to take a look at some of our favorites after the jump.

"Fight Club"

This one's the most obvious comparison that comes to mind. Tyler Durden really is only a manifestation of Edward Norton's unnamed character's alter-ego. He is the exact opposite of his creator, and as the bad apple he gets them into some big trouble. It's no surprise that "Black Swan" was looked at as the female version of "Fight Club" when it was first announced (and the comparison is definitely appropriate).

"Thirteen"

Here's another movie about a good character's downward spiral as brought about by her dark foil, but this one's all the more disturbing because it's about 13-year-olds. Tracy sees in Evie everything that she doesn't have: sensuality, maturity and popularity. She coordinates a meeting with the popular eighth grader (played by "Twilight"'s Nikki Reed) and, after "proving herself" by stealing an old woman's wallet, the two become fast friends. Tracy then gets sucked into a life of sex and drugs (again, at age 13!) that she somehow manages to extricate herself from by the film's end.

"Harry Potter"

Before you attribute this solely to my "Harry Potter" obsession, face up to the fact that few characters in recent pop culture are as obvious foils as Harry and Voldemort. You could make the argument that Harry and Draco also act as foils for one another (and Harry and Neville, and Snape and Volemort), but the opposing relationship between Harry and Voldemort is one of the main plot points of the story. Harry embodies good and knows how to love, while Voldemort only desires power and furthering his evil. How much more obvious can it get?

"The Parent Trap"

After all these depressing films, we figured we'd lighten things up a bit with "The Parent Trap." The two twin sisters who were separated at birth are exact opposites of one another and hate each other upon first meeting, but soon become best friends. They decide to overcome their differences and switch places with one another in order to get their separated parents back together. See, character foils can be used for good, too!

"Youth In Revolt"

This Michael Cera film might not have been the most well-received film in recent years, but "Youth In Revolt"'s Francois Dillinger is purely a manifestation of main character Nick Twisp's alterego. Francois is everything Nick isn't, and everything Nick can't be. He needs Francois to get the things he wants -- the girl, namely -- but in doing so life just gets worse for him. Francois certainly isn't a good influence on Nick, but there sure are plenty of comedic events that occur as a result of his creation.

Who are some of your favorite character foils in film?