Nina Sayers is the main character from Black Swan. She in order to become "the black swan" started to force herself to become someone bad, and put herself through emotional torment to become perfect.
Nina Sayers, a young dancer in a prestigious New York City ballet company, lives with her mother, Erica, a former dancer. The company is preparing to open the season with Swan Lake. The director, Thomas Leroy, has to cast a new principal dancer after forcing Beth Macintyre into retirement. Thomas wants the same ballerina to portray the innocent, fragile White Swan as well as her dark, sensual twin, the Black Swan. Nina auditions for the part, performing flawlessly as the White Swan, but not quite able to emulate the characteristics of the Black Swan. Although Nina does not do well during her audition, she approaches Thomas and asks him to reconsider her as the lead role. He tells her she is the ideal dancer to cast as the White Swan, but she lacks the passion needed to correctly portray the Black Swan.
Nina at first reluctantly accepts this and decides to leave when Thomas stops her and chides her for giving up too easily. Though he praises her technique, he criticizes her machine-like performance, saying that he has never once seen her lose herself. Nina says that she wants to be perfect, to which Thomas retorts by saying that perfection isn't about control, it's about 'letting go.' When Thomas forcibly kisses Nina, she displays a change of character and bites him, convincing him to cast her as the Swan Queen. An intoxicated Beth angrily confronts Thomas and Nina. She is later hit by a car and seriously injured in what Thomas suspects was a suicide attempt. Nina begins to witness strange happenings. Thomas, meanwhile, becomes increasingly critical of her "frigid" dancing and advises her to stop being a perfectionist and to lose herself in the role. Thomas points to Lily, another dancer in the company, whom he describes as lacking Nina's flawless technique but possessing an uninhibited quality that Nina has not shown. The relationship between the two dancers is tense because of Lily's indiscretions, but Lily invites Nina to a night out. Nina is hesitant at first but decides to go against her mother's wishes.
At a restaurant that evening, Lily offers Nina a capsule of ecstasy to help her loosen up. Though reassured its effects will only last a few hours, Nina turns it down. Lily later slips it into her drink at a nightclub while she is absent. Nina returns home late, fights with her mother, barricades herself in her room, and has sex with Lily until the latter seemingly smothers her with a pillow. Next morning, Nina wakes up alone and late for rehearsal. When she arrives at the studio, she finds Lily dancing as the Swan Queen. Furious, she confronts Lily and asks her why she did not wake her up that morning. After Lily claims she spent the night with a man whom she met at the club, Nina wonders she dreamed the encounter. Nina's hallucinations become stronger as she imagines Thomas and Lily having sex in a backstage area and Beth stabbing herself in the face at the hospital with a nail file which Nina drops bloodied in the elevator.
She has a violent argument with her mother, after which Nina passes out. Concerned about Nina's erratic behavior, her mother tries to prevent her from performing on opening night; enraged, Nina stands up to her mother and forces her way out of the apartment. Since her mother had called to say Nina was sick, Thomas assigned understudy Lily to take over, but reluctantly gives way when Nina insists on performing. The first act goes well, until Nina is distracted by a hallucination during a lift, causing her partner, playing the Prince, to drop her. Distraught, she returns to her dressing room and finds Lily there. Lily announces she is to play the Black Swan. Nina shoves her into a mirror, shattering it. Lily seems dead but then she wakes up. Her face changes shape and is now a copy of Nina's. The doppelganger starts to strangle Nina, who then grabs a shard of glass and stabs her rival in the stomach, apparently killing her. The doppelganger's face reverts to that of Lily's. Nina hides the body and returns to the stage to dance with passion and sensuality.
Sprouting feathers, her arms become black wings as she finally loses herself and is transformed into a black swan. At the end of the act, she receives a standing ovation. Offstage, Thomas and the rest of the cast congratulate her on her stunning performance. Nina takes Thomas by surprise and kisses him. Back in her dressing room before the final act, Nina is congratulated by Lily, revealing that their fight was, again, imaginary. The mirror, however, is still shattered. She removes a shard from her own body and realizes she had stabbed herself. Dancing the last scene, in which the White Swan throws herself off a cliff, Nina spots her mother weeping in the audience. As Nina falls backward onto a hidden mattress, the theater erupts in thunderous applause. Thomas and the cast gather to congratulate her—only to find that she is severely bleeding. As the white ceiling lights envelop her, she whispers, "I felt it. Perfect. It was perfect.
- Nina has a Mental Disorder called Alter-Ego, which a new personality lives within her old personality, this personality fight.
- In the film many butterfly figures where seen, that proved Nina was under Monarch Mind Control.
- Monarch Mind Control is a form of mind control which creates a mind control slave by utilizing the human brain's trauma response of dissociation to create a form of Multiple Personality Disorder (MPD) wherein various triggers can cause the slave personality to surface and respond to commands given by the master.