Age: apparently 16
Date of birth: unknown
Zodiacal Sign: unknown
Height: 1.68 cm
Nicknames: Gray Witch, Pizza Girl
C.C. is apparently immortal, healing from any wound (implied to include beheading) with enough time. She also doesn't age. Apart from her immortality, C.C. has the ability to bestow people with the power of Geass, which manifests differently in each person but generally carries the ability to affect the minds of those it is used on in some way. The Geass sigil glows on her forehead whenever she manifests this power, and she has a similar scar on her left breast. It is hinted that many more like her exist, as shown in her memories of many children with similar sigils, and she suggests that the power has precipitated bloody conflicts in the past. Her powers caught the interest of Britannia, who imprisoned her for experimentation purposes.
Before she gained the power of Geass, C.C. was a ten-year old escaped slave. A church nun gave C.C. the power of Geass, making everyone around her fall in love with her. Once C.C.'s power evolved to its highest point and she grew tired of all the proposals and gifts, the nun transferred her immortality to C.C., allowing her to die while leaving C.C. in the position of repeating the cycle.
In the first season finale, C.C. triggers a trap set by V.V., causing herself and Lelouch to be submerged in a shock image sequence similar to the one she used on Suzaku. Through this, Lelouch sees memories of her past, including repeated "deaths". One shows C.C. attempting to escape from a battlefield, only to be shot in the forehead. Further memories show her being persecuted as a witch and suffering various forms of torture and/or execution throughout history and various time periods, including burning at the stake, guillotining, and the iron maiden. This would suggest a minimum lifespan of at least six centuries. In a special feature included in the series' fifth DVD, she and Lelouch discuss Washington's Rebellion, during which she speaks of participants such as George Washington and Benjamin Franklin as if she had been close friends with both. In the past, she appears to have observed Suzaku and Lelouch when they were both children, having even interacted with Lelouch at one point, though he doesn't remember their meeting.
Her individual experiences have led C.C. to become a detached and lonely individual, with little care for even those she has entered into contracts with, while in the past she was somewhat a spoiled and cheerful girl. She tells Lelouch that she has been alive so long that she can no longer remember who loves her and who hates her. Due to her nature and history, she has been lonely as long as she can remember. Lelouch replies, "You're not alone. We are partners. If you are a witch, then I shall become a warlock." Lelouch is possibly the first person that has ever truly cared for her and it appears that she reciprocates at least some of these feelings, as she unexpectedly kisses him after their memories are shared.
C.C. has a strong penchant for pizza , especially Pizza Hut 's (which sponsors the show in Japan, though the logo is blurred out in the English dub); she constantly orders pizzas to Lelouch's house using his credit card. She also carries around a stuffed toy of "Cheese-kun", the company's mascot in Japan. Her love of pizza is often used for comedic effect, as she was twice willing to risk capture simply to get a piece of a giant pizza being made by the Student Council (which is ruined both times); she doesn't trust Lelouch to retrieve it for her. Both Lelouch and Kallen sometimes refer to her as "Pizza Girl".
When left alone, she has sometimes spoken to a previously unknown person through means unknown, which, in episode 23, was revealed to be Marianne, Lelouch's deceased mother, although in episode 19 it appears that she is talking to V.V. as well. According to the DVD Magazine 02, she is talking to more than one person when she seems to be talking to herself. In the past, it was shown that she and Marianne were close.
C.C. is introduced in the first episode, where she emerges from a fake gas capsule seized by Japanese rebels. She saves Lelouch Lamperouge from the Britannian soldiers trying to recapture her, taking the shot intended for him. To keep the soldiers from simply shooting again, she grants him the power of Geass, which she calls the "power of the king", on the condition that he grant her greatest wish. Lelouch accepts and is granted the power to control people's actions. Since she appears to have died following this, he leaves her body behind.
She unexpectedly reappears in the fifth episode, casually folding origami with Nunnally. From this point on she passively oversees Lelouch's missions as Zero, wanting to keep him alive so he can fulfill his contract, often going as far as wearing his clothes and impersonating him when situations become life-threatening.
When C.C.'s existence is revealed to the Black Knights, she gains considerable unofficial standing, as she is seen by other members to be one of Zero's closest advisors, if not his top advisor. However, her willful attitude and lack of an official posting annoys some veteran members and causes confusion as to her role within the Black Knights. At one point, Tamaki goes so far as to accuse her of being a member only because she's Zero's lover, a claim which she coldly denies. When the Black Knights gain possession of the Knightmare Frame Gawain, she becomes its pilot while Lelouch operates the weapons.
In the season finale, she uses the Gawain to battle Jeremiah Gottwald's Siegfried so Lelouch can save his sister. She drags both it and herself to the ocean floor to end the battle while narrating that the spark of Lelouch's actions was the core of human motivation: the desire for just a small amount of happiness. According to Yukana in a conference memo, C.C. was crushed by the water pressure, but being immortal, ultimately drifted to the surface and revived; it is stated that it was too gruesome to be shown.
At the start of the second season, C.C. appears to be commanding the Black Knights. She and the rest of the surviving Black Knights initiate an operation to unlock Zero's memory that was sealed away by the Emperor of Britannia. Despite the Intelligence Agency having followed Lelouch in anticipation of that exact outcome, she is successful in restoring his memories. She takes up her old position following this.
She is revealed to have formerly led the Geass Directorate, a secret organization that studies and produces Geass users. V.V. succeeded C.C. as the leader, and relocated the headquarters to somewhere in the Chinese Federation. After pinpointing the location of the Geass Directorate, Lelouch orders C.C. to lead the attack against it. Some of the scientists recognize C.C. and beg her to save them, but they are killed before she can answer. She also reluctantly kills V.V.'s direct subordinates when they attempt to escape by bullet train in order to bury the existence of Geass. Her past is revealed to Lelouch after he is transported to the Sword of Akasha to face the Emperor. She also reveals that he would have become immortal had he granted her wish, which is to die, and spares him by offering her life to the Emperor. Lelouch refuses to let her die unhappy and rescues her, but she loses her memories of Geass and the related abilities, reverting to her personality as it was before she came under the contract that ultimately bestowed immortality upon her.
When in close proximity to another person, C.C can afflict them with a hallucinatory experience of chaotic and ominous images, pertaining in part to the memories of the target involved; the content varies with the afflicted. Physical contact, either direct or via a Knightmare Frame, may facilitate the process. Suzaku is shown images of his father (whom he murdered) as well as parts of C.C.'s memories, driving him into a panic. In another instance, Anya is shown images of Lelouch's childhood, causing her to freeze in wonder until contact was severed. It tends to activate involuntarily at various points, such as when Lelouch's Geass becomes permanently active.
Apart from psionic abilities, C.C. is a capable leader, able to rescue Lelouch from Britannian traps, and handle firearms with some proficiency. She is also an accomplished Knightmare pilot, able to pilot both standard Knightmare Frames as well as copilot the Gawain with Lelouch.
Before becoming immortal, C.C.'s Geass, gained in her contract with a nun, granted her the power "to be loved," the ability to make anyone around her love her. It first manifested in her left eye, eventually maturing to permanently active sigils in both eyes. Once it reached its full potential, the nun who granted her the power forced her immortality upon C.C., giving her Geass sigil on her forehead and the similar scar under her left breast. As part of the exchange, C.C. became immune to the effects of Geass while losing her original power.