Zero Two (ゼロツー, Zero Tsū) is the main heroine and the deuteragonist of DARLING in the FRANXX. She is a human-klaxo Sapien hybrid and a member of the APE Special Forces, primarily fighting on the front lines.
Zero Two's personality is rumored to be dangerous, cold, and alluring as she grew up. Her outlook on life is quite cynical, so she didn't bother with a name since they are all meant to fight and die.
When people around her fail, she hardly bats an eye at it because, to her, it is just a fact of life that everyone dies. Zero Two always keeps people at arm's length with mocking humor, nihilism, and emotional detachment. Zero Two also freely talks about how much she hates society.
It is later seen that Zero Two is a very unruly, passionate, fierce-tempered, self-confident, smug, assertive, and carefree girl who hates to follow the rules set up by the adults.
Character Background (Major Spoilers):
Zero Two is created by Dr. FRANXX out of the Klaxosaur Princess's DNA. Many specimens like Zero Two were born but failed to survive, making her the only successful human-klaxon sapiens hybrid. Because of her high Parasite potential and potential in general, she received the code number "002".
She did not receive the same regular training as other children in the Garden to become a Parasite. She was trapped in her room for so long that she described it as being kept inside forever.
When Hiro witnessed Zero Two's suffering several times during her training, he made up his mind to rescue her. When Hiro came to save her, Zero Two had just gone through testing and was curled up on the floor. Hiro shattered her window with a searchlight, and although Zero Two was initially aggressive, she was moved by Hiro's tears and began crawling towards his outstretched hand.
The two went outside and started to run away. However, Hiro's attempt to run away with Zero Two failed. Both of them got sent to their rooms, and the two never see each other again.
Since Zero Two's meeting with Hiro did leave a significant impression on her, she swore since that day to become human since if she were like him, they could always be together. To make her even more determined, people also convinced her into thinking that she could become human by killing Klaxosaurs by Papa and the others.
Timeline:
During the welcoming ceremony, Zero Two engaged in a battle with the klaxosaur, and met Hiro, and offered him to be his partner. The two have paired for the first time, and their pairing unlocked the "Iron Maiden" form of the Strelizia. This transformation caused them to kill klaxosaur with ease.
During the discussion for Hiro's promotion test, Zero Two volunteered to be his partner; however, group leader Ichigo opposed her request.
When Zero Two paired with Mitsuru during the Conrad-Class klaxosaur mission, Mitsuru couldn't bear Zero Two's power and passed out. This incompatibility induced that Hiro should be Zero Two's pair, and they became pairs afterward.
The new pair breed an incredible success, and eventually, the group was awarded by Papa. At the same time, Zero Two started to feel worse and more aggressive for an unknown reason. Her fierceness caused her to go demon during a conversation with him. Hiro tried to calm her down, but Zero Two started to strangle him, which triggered her memories to Hiro.
When the two shared their memories, they realized they had known each other since their childhood, and Hiro was why Zero Two searched for her "darling." The two apologized to each other and eventually confessed their love.
Later on, Zero Two learned the whole story of their world, plantations, FRANXX's, and klaxosaurs after meeting Dr. Franxx. Zero Two also learned their true enemy and finds herself in a situation where only Hiro and herself can save the world.
After the long-running battle with VIRM, Zero Two went into a catatonic state (mysterious scratches, unboundedness, her horns getting crumbled). After a while, Hiro figures out that Zero Two's soul has emerged into evolved Strelizia.
At the end, Zero Two decides to sacrifice herself to save the world, but suddenly Hiro comes and offers to help her, saying that they can't be apart anymore. The two enter the gate leading to VIRM's planet, and approximately two years later, they engage in their final battle with VIRM. The two save the world; simultaneously, they happily sacrifice themselves for their planet and friends.
A thousand years later, a young boy who resembles Hiro meets a young girl who reaches Zero Two. The young girl trips down on the roots, and the young boy picks her up. Then the girl asks for the boy's name, and he introduces himself. It is revealed they are the reincarnations of Hiro and Zero Two, and a new story of romance begins.
