X

X is the successor to the original Mega Man and is Dr. Thomas Light's greatest creation. X was the first robot to possess free will, sentience, and independent thought, no longer requiring restrictive programming or rules to dictate his behavior, making him the first known Reploid. Dr. Cain, the scientist who discovered him sealed away by Dr. Light, used X's general architecture in order to put Reploids into regular production, starting a new age of robotics. As a more advanced successor to the original Mega Man, X's design is more detailed and mature-looking. He shares his predecessor's predominantly blue and cyan color palette, but is taller and appears to be in his early teens (likely fourteen or fifteen years old, given his initial AI setting and height, whereas the old Mega Man was about ten years old). His upper torso is covered by a segmented chest plate with shoulder pads. His joints, such as his knees and wrists, have small black tabs on them. His helmet has cyan ridges atop it and above the visor, and a red lens sits on his forehead.

X was designed by Dr. Light as a robot who could think and make his own decisions without programming limitations. Unlike most Reploids, X is unique in that his consciousness was tested by diagnostics for over 30 years before he was released into the world. This gave him a reinforced sense of justice and mercy, and ensured that he would never choose to harm a human or go Maverick, despite having the unlimited choice to do so.

Unlike other robots of his time, X was created with a unique intelligence akin to that of a human conscience, allowing him to think, feel and act completely on his own, along with highly advanced and adaptable body technology. Light dreamed that X's technology would someday give all robots the ability to learn and grow like living beings. However, Light was not without foresight, and was approaching the end of his life with no successor to continue his work on X. To ensure the reliability of X's conscience, Light prepared a stasis capsule to perform system tests on his AI, which would take approximately 30 years to complete. He also included a great number of viral counter-measures in X's system, ensuring he would never succumb to any virus. Finally, Light left a final message including his hopes and fears, wishing for X to be a champion of peace in the future. On September 18, 20XX, X was sealed away. An unknown amount of time after completing his 30 years of diagnostics, X was awoken in the following century in 21XX by Dr.Cain.

True to his destiny, X is a very human robot. He is a kind soul who wishes for nothing more than peace between humans and Reploids. However, he holds no tolerance for injustice and takes his quest for peace very seriously. In times of conflict, he is a hot-blooded warrior who is compelled by his emotions over logic. He always stands up for what he believes is right and fights to protect the innocent. Even so, X remains sympathetic for the Mavericks he fights and often tries to reason with them before it comes to violence. Unfortunately, X's emotional commitment also makes him easily frustrated when things go awry, and he rarely understands the extreme motives of his Maverick opponents.

Though X fights with all his might against Mavericks, he is a pacifist at heart, echoing the wishes of the original Mega Man and Dr. Light. Many battles end with X pontificating on the paradox of achieving peace through violence. Despite this inner conflict, X always come to terms with the reality of the situation and understands that he must indeed fight in order for the peace he desires to become a reality. Sometimes he requires the influence of friends such as Zero or Axl to keep his motivation going. Despite his peaceful nature, X has an informal and impolite manner of speech.

X's best friend is Zero, at times even calling him his "only friend" due to the unique depth of their bond. At first, X looked up to Zero as a role model as Zero was his mentor and teacher during his early days a Maverick Hunter, often calling Zero Senpai, but the two grew close through their time as Maverick Hunters together. X admires Zero's cool temperament and unbreakable will, while Zero admires his passion and pure heart. Upon gaining hints of Zero's past as a Wily robot, X began to worry that he may have to fight Zero someday. Conversely, X initially dismissed Axl as a troublemaker, seeing too much eager violence in him that he once practiced as well. Over time he came to respect Axl by witnessing his strong moral compass, and realizing that his courage to fight even in the face of hardships is one of his greatest strengths.

X fears one day Zero will leave him and never return, causing him to often unhealthy check up on Zero if they haven't seen each other all day, to make sure Zero is still there especially after Zero died two times and went missing for a while.

Several years later after the events of the Mega Man X series, X finally ended the Maverick Wars. He did so by erasing the Sigma Virus with the help of the "Sigma Antibody Program", also known as the Mother Elf, which had been reverse-engineered from Zero's internal workings. This led to a period of peace, even though X was alone with Zero remaining in stasis. Some time afterwards, the human scientist Dr. Weil proposed Project Elpizo, a plan to create a perfect ruler to control all Reploids to end Maverick behavior. X disagreed with the project, believing Reploids and humans to be capable of co-existing peacefully. Secretly, Weil corrupted the Mother Elf into the Dark Elf, starting the "Elf Wars" to prove the unreliability of Reploids. Weil also used Zero's body to create Omega, requiring Zero's "mind and soul" to be placed in a new body created by Dr. Ciel's ancestor so he could help X defeat Omega. For the unprecedented suffering Weil and Omega caused, Weil was modified into a cyborg and banished to the wasteland, while Omega was exiled into Earth's orbit. With the end of the Elf Wars, Zero sealed himself away once again, trusting that X could protect the world as leader of the utopian city Neo Arcadia. X attempted to stop Zero's encapsulation, but by the time X arrived to halt the procedure, it was already halfway finished, although not before Zero offered words of encouragement to X. It was presumably around this time that X retrieved Zero's Z-Saber again, which he would keep for years. To help repair the world and protect Neo Arcadia, the Four Guardians were made based on X's DNA.

However, Maverick attacks raged on due to the lingering influence of the Dark Elf, and X grew weary of his long life of war with no end in sight. He began fearing that he would lose himself and become worse than the Mavericks he faced. After all attempts to contain the Dark Elf failed, X used his own body as a seal, locking the Dark Elf within Yggdrasil. The burden of becoming the seal caused his mind to be removed from his body. X's soul persisted in the form of a Cyber-Elf, secretly watching over Neo Arcadia. Cyber-Elf X persisted until the end where Zero killed Omega, where he used up the last of his power helping Zero and finally dissipated, entrusting the world to his friend's hands as he had done with X years ago. He couldn't handle the new responsibility for Neo Arcadia anymore because Zero left him all alone again. X never admitted but Zero was what kept him going during the harsh war periods, if he had choose between the world or Zero. He would choose Zero over the world even though he knows its selfish of him.