The horror genre has long served as a space for confronting female sexuality. In Darren Aronofsky's graceful and gruesome ballet film Black Swan, the doppelgänger, or evil double, is used as a trope for examining women's supposed inner doubleness--the good old Madonna and the Whore syndrome. The movie delves into the concept of dirty female purity by way of another unsettling binary, death and desire, and particularly its place in ensuring the brittle Nina's (Natalie Portman) success as a dancer in a dual role.
Nina must assume the form of both the black and the white swan in Tchaikovsky's Swan Lake (a ballet conjured from the same polarizing realm of folklore as The Red Shoes, which clearly influenced Aronofsky here) and the sexualized woman in society. Ultimately, the more erotic, self-destructive, and close to death she grows, the better she dances, and the more her audience and ballet director (Vincent Cassel) want her. In this cinematic exercise in the uncanny, as Nina adds more bad girl to her good girl persona and becomes a better dancer, she starts seeing more of her evil twin, both an exact replica (Portman) and a double who plays the "whore" to her "virgin" (Mila Kunis, oh my).
In the world of this film, men need to perceive women in this twofold manner in order to desire them. The love object must be bad enough to want to bed, but just good enough that it's considered a conquest to do so. However, what is perceived as a dramatic play of opposites in a woman is actually just the architecture of a complete person. Everyone has "bad" and "good" inside; yet instead of dealing with the whole Nina and the desire she incites, the ballet director compartmentalizes her into two poles that can be dealt with separately.
To embody opposing forces is an annihilating prospect, psychologically speaking. Nina can't dance both the black and the white swan at once, so she falls prey to a common problem of women cast in the virgin-whore dyad: because she's never allowed to coalesce into a balanced whole, her two halves destroy one another. She transforms into the ballet director's "little princess" only once she becomes eroticized and right before she self-destructs. By the film's logic, the longing for the female who can preserve her childlike purity while simultaneously being a sexualized woman is the impossible fantasy that rips her apart.
While descending deeper into her black-and-white-swan-ness, Nina shatters the ballerina that dances in a music box by her bed each night. Later, the doll pirouettes on the broken leg that is all that remains of her. There is in women a carnality that has yet to be codified and therefore remains invisible in the conventional vision of her. As Nina finds ever-worsening scratch marks on her back, we begin to wonder if it's the full spectrum of female sexuality, neither virgin nor whore, that is trying to claw its way out, a severed limb that keeps dancing long after the rest of her has been smashed.