Lucy (Elfen Lied)

"You know who isn't human? You know who isn't human?... PEOPLE LIKE YOU!"

- A young Lucy to the bullies and the girl before dismembering them.

Lucy is the protagonist of Elfen Lied. She is the Queen Diclonius, an evolutionary offshoot of the human race.

Personality
Kaede has Dissociative Identity Disorder, having at least three personalities called alters. This disorder began in her childhood. Kaede, Lucy, and Nyu are the three main alters/personalities.

Kaede and Lucy
Her original personality (Kaede) was that of a depressed, distrustful, withdrawn and frustrated kid. She was discriminated against by others, because of her horns. Thinking that she was abandoned by her parents, she was also ostracized by the staff of the orphanage, bullied and treated contemptuously by other children, all this because of her horns. She didn't understand why such discrimination happened, and so she also suffered from self-hatred from having horns. To some extent she understood that the other kids were miserable and needed to make others miserable too, targeting especially those already more miserable than them. When gaining intimacy with someone as Kouta and Aiko, she is shown to be sweet, kind and shy.

After witnessing her dog's murder at the hands of the orphanage bullies, Lucy began to develop a deep hatred of Humans, killing whole families just to use their house, without regret or guilt. Shortly after this, Lucy and Kaede began to hear a voice in their head, supposedly the voice of the body's DNA. The voice of her Diclonius instincts had the mental image of herself, with the only difference having a cold and sadistic expression. The voice told her that she couldn't coexist in a world with Humans, and then said: "Join me. Then I will make to you a place to live in.". From that point on Lucy began to listen to her instincts, killing some Humans by way of inducing heart attacks, and spreading her genes to Male Humans, who would have Diclonius children who would in turn kill and infect more. Her Diclonii instincts began to overpower her, leading her to become more sadistic and psychopathic.

Nyu
During her escape from the Diclonius Research Institute, a sniper shot a bullet from a .50 caliber rifle on Lucy's helmet, that was partially slowed by the helmet she wore and her vectors, causing her to fall off a cliffside into the sea. Lucy's personality fell unconscious and by the next morning Kaede woke up on the beach at Kamakura without any memories and with a childlike and infantile personality. The only sound she knew was Nyu, which was how Kouta and Yuka decided to name her. Despite the ignorance of Nyu, she had a basic sense of good and evil, much like a young child. She was a kind, sweet, innocent and naive girl, with an intense sexual curiosity that often made life awkward for her housemates. As the time passed in the Kaede House, Nyu slowly began to learn the basic morals and norms of society. When she lost her horns in the battle with Mariko, Nyu's persona predominated, and remained for just over half a year. During this time Nyu matured greatly, learning how to speak properly and in complete sentences, how to cook, clean, and show at least some restraint on her sexual curiosity. A variant on this personality emerged when Kaede House was attacked, as Nyu was finally able to use vectors like Lucy, was brutal towards her attackers, but still deeply caring of her house mates, especially Kouta. It could be said that the personality she finished the series with was a variable-percentage merger between Lucy and Nyu, as elements of both surfaced. For example, when facing Chief Kakuzawa for the last time, her nudity became an issue for her, covering what she could from his view. This is in marked contrast to the uncaring attitude the pure Lucy persona had about such matters, likely stemming from contempt for Humans as lower creatures, and also to the child-like free spirit Nyu mostly was, happily climbing in the bath with and groping to excess any friend who had her attention. Upon her death, these two personalities each seemed to have their own spirit, both of which loved Kouta and her friends.

DNA Voice
It cannot be confirmed from evidence in the series whether or not this personality, supposedly the voice of Lucy's Diclonius DNA, really existed or was merely the embodiment of Kaede's intense alienation and pain. Kaede first truly heard it after her rage and grief over the killing of her puppy at the orphanage, and heard it even more as she feared Kouta had betrayed her. It was a compelling voice that Kaede often gave into, yet she stated that it never actually controlled her, and merely guided her. Nana seemed to hear this voice on at least two occasions on which she felt she had no place in the world, and Mariko clone Barbara said that she heard a voice urging her to kill all Humans. Yet both Nana and Barbara suffered cruelly at the Institute, and the validity of these instances is in question. The idea that it may have been more of a split personality than an actual echo of Diclonius DNA is given strength by the fact that it finally did briefly take over Kaede's body as it was close to death. Kouta for his part dismissed this voice as a variant on something all people have to struggle with, but best evidence also contains no information from the anime or manga that dismisses this possibility either, leaving it an open question and one of the series' greatest unresolved mysteries. The personality of Kaede/Lucy/Nyu's DNA Voice was that of a cold, sadistic, hate-twisted, manipulative, compulsive/obsessive and truly psychopathic killer without guilt or remorse. She had a strong wish to destroy all of Humanity and replace it with Diclonii, in which she would possibly rule the world, since she is in essence a Queen Diclonius. She also had no qualms in trying to convince Kaede/Lucy/Nyu that all Humans were vile creatures that truly needed to die, and was even willing to kill Kouta and Co. at any cost, regardless of their compassion towards her. Near the end of the manga series when she manages to gain full control of her then mortally wounded body however, and Kouta is urged by Kaede and Nyu to shoot and kill her with a near-by gun, he backs down at the last moment, unwilling to kill his long-time friend no matter how much she wronged him in the past, even though Kaede's and Nyu's illusions are now fading away, unable to protect him anymore, and the DNA Voice is now in full control.

Despite this sudden freedom to finally kill him and his friends/family as she pleases, the DNA Voice, seemingly shocked/surprised and perhaps even moved by Kouta's love for her, instead ceases all attacks, only to use a single vector to pick up the gun for Kouta to shoot her, which he finally does, thus putting her out of misery. This suggest that despite all the horrible deeds she committed in the series, whether directly or indirectly, she was still capable of compassion, even if just a tiny bit. It is also possible that, having never been in control and therefore fully 'alive' before, this persona had no tolerance for physical pain, let alone the intense agony Kaede's body must have undergone as it melted.

Alternatively, it was Lucy herself, not the DNA Voice, who ended the rampage; if the DNA Voice is the embodiment of her instincts, then it had no reason to stop its rampage. Furthermore, it had never shown any hint that it would ever be moved by anything other than its desire to eradicate mankind. Therefore, one could infer that its seemingly inexplicable decision to stop killing was, in fact, Lucy herself mustering up the strength to defy her very nature in order to obtain peace. Due to the ambiguity of the nature of the DNA Voice, it is unknown if she was ever reborn at the end of the manga series.

Trivia

 * Lucy and her half-brother are the only Primary or Monarch Diclonius in the series; All others seen or spoken of are Secondary, or Silpelit Diclonii. Lucy and her brother could have/sire children; all the others were sterile.
 * Lucy appears to be named after a Female Human fossil named Lucy, an Australopithecus whose DNA resides in most Humans living today, and at the time considered the oldest. Since Elfen Lied concluded, older fossils have been found.
 * Even though the first lives Lucy took were children (Tomoo & his companions) (which is considered one of the most evil things a villain can do), viewers despised the victims so much that Lucy not only received little to no controversy for her actions, but rather earned sympathy and even some praise & understandment.
 * Lucy is slightly similar to Jason Voorhees. Both characters are victims of bullying & are disgusted due to their deformed appearances, both never harmed animals, both have the highest tolls of body counts for their victims & both became mass murderers after they couldn't cope of losing someone they love dearly (Lucy: her puppy; Jason: his mother). Unlike Jason however, who doesn't spare anybody except children and animals, Lucy kills children & is shown to spare certain people she loved dearly.