Black Swan
Wow wow wow. Wow.
The Swan Queen, a role requiring one's identity to harbour to two polarising ones. To stay as a White Swan which is all that Nina had ever known, not by choice but by maternal force or to find and embrace being a Black Swan, an identity shift required to achieve her only known ambition.
Nina isn't slowly nurtured to become a Black Swan, a symbol of a liberated self; a transition from childhood to adulthood, she is forced to become one abruptly after years of being suppressed.
Dance is all she knows, a perfectionist, by nature, would lose their self when faced with such a hurdle. When you don't have a plan B due to your entire worldview being controlled since birth, you are forced to make the jump. Whether you pass or not the skyscraper of a hurdle you end up falling and meeting your demise anyways. Splat.
The question being answered here is whether Nina lost herself or she found her true self. She wanted to be perfect and she believed she was. She did it how SHE wanted to, just like a liberated soul.
Natalie Portman the woman you are. THE greatest performance I've seen so far of any actress in my existence. If you visualise a spectrum on one side the characteristics of a White Swan and the other the ones' of a Black Swan throughout the film, you'd notice how perfectly fluid she is portraying said spectrum throughout different parts of the film. The score brilliant. The way the ending panned out is nothing short of genius by Aronofsky, possibly one of the greatest endings I've seen.