Zero was created in the early 21st Century by Dr. Albert Wily, who learned from previous mistakes and went on to build one of the most advanced robots ever made, even in comparison to what was to come. Largely, like Dr. Light had done with X, Wily combined every tool and trick in the book when creating Zero, including the ability to think and feel freely like a human, and the ability to harness and run off of the Evil Energy. Unfortunately, this medley caused Zero to be rebellious and too powerful to be controlled, which was discovered quite quickly in his conversations with Dr. Wily while being built. This led Wily to seal Zero away, mostly complete, to hopefully re-awaken later when he found the means to keep his greatest creation leashed.
Unfortunately, that never happened, but the good doctor - always one step ahead of the game despite his near insanity - built a time release system into Zero's capsule, which was set to awaken Zero after a certain time if he had not been awakened manually by Wily himself. This occurred several decades later - in the 22nd century - and arguably changed the course of history for the entire world. Zero was found by Maverick Hunters under the command of the then-sane Sigma, who were immediately overwhelmed and reduced to junk by him. After wiping out an entire squad, Zero was confronted by Sigma himself, and despite the Hunter Commander's skill and power, eventually found himself at a disadvantage. Zero was preparing to kill Sigma when a failsafe Wily had installed activated, causing Zero to reel back in pain and giving the battered and mostly-dead Sigma an opening to finish the fight. Focus Crystal Broken, Zero fell unconscious, and was taken to Dr. Cain - who had chanced upon X - who in turn repaired him.
Zero's confrontation with Sigma had freed him of the influence of the Evil Energy, and eventually became a top Maverick Hunter. He soon met X, and the two became fast friends and close comrades. Unfortunately, Sigma had caught the nascent virus held within the Evil Energy when he fought Zero, and thus, Sigma himself turned Maverick, and began a long, bloody revolution to be later called the Maverick Wars. X and Zero fought tirelessly against Sigma and his Mavericks, with Zero dying or being disassembled in the processes, along with being resurrected and reassembled several times over as well. At times, Zero was also a target of the Mavericks to be used against X and the others, his pieces captured by a group called the X Hunters early on in the war, and then later as part of a plot by Sigma to have Zero once again come under the influence of the Evil Energy. Dr. Wily himself even visited Zero to attempt to turn him back to his "true self," appearing to the ex-Maverick in nightmares from beyond the grave.
In the end, X and Zero were able to finally end Sigma's reign, but it had all come at a cost. Along the way, Zero had fallen in love with a reploid girl by the name of Iris, but unfortunately they found themselves on opposing sides since she was part of the Repliforce. Colonel, Iris' brother, was a high-ranking officer of Repliforce, and once relations between the Repliforce and Maverick Hunters broke down, the two were destined to fight. Zero destroyed Colonel in a fateful duel in which neither held back, and Iris - blind with grief and anger - attacked Zero by combining her programming with her brother's control chip and utilizing a powerful Ride Armor-like form. Never one to hold back, Zero fought with everything he had despite his reservations, and accidentally damaged the exterior power core of the form, causing a massive blast that unfortunately damages Iris beyond repair, who then dies in Zero's arms. Zero is also forced to fight X on a few occasions as well, severely wounding his best friend and almost getting them both killed by Sigma.
Near the end of the war, Zero comes to the discovery that although he largely remains resistant and free of the influence of the virus born with his creation, he still carries it, and is actually the one who spread it across the world during his time, ironically enough, as a Maverick Hunter. He willingly gives himself up at the end of the war to be sealed away, and eventually has his control chip (his mind) and his body separated for research on a possible cure.
Although a cure is eventually found, and peace is established between humans and reploids, said peace is not lasting. Relations between humans and reploids eventually break down, and the Mother Elf - a program designed to help cure the virus and keep reploids from ever going Maverick again - is corrupted by Dr. Weil. Zero is brought back in a copy of his own body to help X and the others end the conflict, his original body having been stolen and also corrupted by Weil.
Brought into another war, Zero found himself in many ways in the exact opposite position than he was during the Maverick Wars. Instead of fighting to protect the status quo, Zero found himself aligned with a Resistance force, and eventually having to fight not only his original body in the form of Omega, but a copy of X as well along with reploid guardians modeled after aspects of the hero. Despite encountering increased resistance, and even the loss of X himself, Zero fights on, resolving to make good upon a promise to fight for those he believes in, and safeguard the world that mattered so much to his best friend. Although originally dubious of Ciel, Zero also comes to trust the altered girl, and forges bonds with the entire Resistance, going so far as to ensure their casualties are minimized while under his watch.
End the end, Zero was able to destroy Omega, Wiel, and the threat they posed to the free humans and reploids of the world. Once again seemingly sacrificing himself to ensure Wiel and the Space Station Ragnarok are destroyed. Many mourn the loss of Zero, but Ciel seems to believe that Zero survived...
Many of the energies within Ragnarok were highly unstable, especially given the experimental nature of many of Wiel's creations. The explosion largely destroyed Zero's body, but as always, did not put the reploid down for good. Fragments of the Ragnarok - along with remnants of Omega hidden with in the ship were ripped into the multiverse during the explosion, as was what remained of Zero. The powers that be in the multiverse found it fitting to have Zero's creator find what remained of his masterpiece, and secretly began work of rebuilding the reploid. Deep within the heart of the an old faction's headquarters, an ailing Dr. Wily managed to rebuild Zero from what remained of both his original and new bodies, along with restoring Zero to his "original" self. Before Zero could be awakened, however, the evil scientist-turned technomancer is chanced upon by a certain Keyblader-Wielder-in-training, and decides to launch Zero's pod up through the ruins and into the Tower of Twilight. Wily's death at the hands of Ventus triggers yet another failsafe, slowly awakening the reploid from his slumber.
Powers and CapabilitiesEdit
Since he is a highly-advanced reploid designed for combat, Zero sports heavy armor which protects him from most conventional and ballistic weaponry, as well as a sensor array which allows him to detect and lock onto enemies over several different sensory wavelengths. His strength is far beyond that of a human's, as his his eyesight, and in most cases does not need air to function.
Like most "Mega Men," Zero possesses a Buster cannon on either or both of his arms (since he can use a Double Charged shot in some games, he might actually have one on each arm). Like Mega Man and X's Buster, the Z-Buster is capable of firing small energy/plasma bullets which vary in size and shape depending on how long Zero charges and how much power he puts into each shot. Also like X - including his upgrades - Zero is capable of charging large amounts of energy into his Buster, which takes time, but allows him to fire off shots that are exponentially more powerful than the quick, simple shots normally fired by the Buster. Most Busters have 3-5 general "levels" of charge, including Double-Charges.
Zero's weapon of choice, and his iconic weapon, is the Z-Saber, which is basically an extendable sword made out of pure plasma/energy similar to Buster fire and other energy weapons in the series. The Z-Saber seems at least as powerful as a Charged Buster Shot, but has the advantage of being able to be used in quick succession, as opposed to the shots which take time to, well, charge. Zero does usually need to get close in order to use his saber, but on multiple occasions shown the ability to fire off blades of energy by swiping with saber through the air, or grow it far beyond its normal size when pulling off particularly powerful attacks. The Z-Saber also seems to possess some limited elemental-channeling ability, as Zero can charge different elements throughout via the Learning System.
The Learning System, which is similar to Mega Man and X's Variable Weapon Systems, allows Zero to learn techniques from high level Mavericks he faces in combat. Unlike X, however, Zero generally doesn't draw upon learned techniques using his Buster, but instead utilizes them using usually his Z-Saber or even his bare hands. This gives Zero access to different elements and powers he would not be able to utilize otherwise.
Zero utilizes a plethora of other weapons, from alternate swords, to halberds, to variable rods based on modified Z Saber technology. Basically, Zero can, and has, utilized particle and energy versions of most conventional ranged and melee weaponry, including spiked knuckles. In the Zero series, he can also use the Zero Knuckle to simply rip off weapons from enemies, and use them as his own.
As a robot programmed for the purpose of aiding in world domination, and ultimately for destroying Mega Man, Bass, and any Mega Man-like robots, Zero has the capability to think quite quickly on his feet, and use variable methods and tactics quite quickly and fluidly in order to adjust his fighting style to fit the situation. Unlike X, he never hesitates when he fights, so takes every opportunity to end a fight as quickly and decisively as possible, even if that means lethal or cruel attacks.
Finally, since he was created to harness the power of the Evil Energy and subsequent viral incarnations, harmful viruses that weaken or harm most robots either are resisted by Zero or even empower him.