Zero is a Maverick Hunter that is best friends with Mega Man X. Both X and Zero and later on Axle hunt down Mavericks. They have stopped Sigma and other evil forces time and time again. So what is Zero's background well I'm going to give more details about Zero, who is my favorite Mega Man X character by the way. Anyway, here we go.

Zero was created by Dr. Albert Wily near the end of Wily's life. While Wily was alive he started developing plans for Zero as seen in the Mega Man fighting games and his other project. Wily created Zero his finest masterpiece and the most powerful thing the world had seen. Wily's other project was a virus inside of Zero. This virus increased Zero's power it also made him not only more powerful but violent. Zero came with the virus, his buster and a saber. He also posses great strength with a single punch able to punch through walls of steel. However, Wily did not leave to see his creation activate.

Several decades passed and Dr. Cain found X, who was lights finest creation. Dr. Cain created reploids based off of X's design. Some of these reploids went haywire and became mavericks. The Maverick Hunters were formed to eliminate these threats. Dr. Cain built Sigma. Sigma was the leader of the Maverick Hunters. X also join the Hunters and started to rise up in ranks. Around this time Zero awakens in the ruins of Dr. Wily's lab.

Sigma received reports that a dangerous red maverick had wiped out several maverick hunting units. Sigma decided to engage Zero himself. Zero nearly killed Sigma before the Wily symbol started glowing in Zero's jewel causing him pain. Sigma used this to knock out the Maverick. Zero was brought back to the hunters. The virus left Zero's body and entered Sigma's. At first Sigma seemed fine. Zero became a high ranking hunter along with X. Then Sigma went maverick due to his programming merging with the Virus. The Virus was called the Sigma Virus. The virus true form is that of a computer virus.

With Sigma now a maverick. Zero became co-leader of the Hunters along with X. Together they took down Sigma's Army. X and Zero defeated one of Sigma's top mavericks named Vile. Zero though was wounded and was believed to have been dead.

However, 6 months after the events of X1 a reploid named Serges built a new body for Zero from scratch. The new body was the original which was still mysterious. However, X had the control chip. X retrieved all of Zero's parts from Serges, Agile and Violent. Zero was rebuilt and his original form. X and Zero took down Sigma again. However, Sigma as he lost stated that Why was Zero a Maverick Hunter as he was the last of Wily Numbers. In the American version he says he is last of the Doctor's creations

Zero would team with X several times to take down Sigma and his schemes. In X4 though Zero was heartbroken. Due to Sigma manipulating and spreading the virus. Zero was forced to kill his friend the Colonel. He was also forced to kill his girlfriend Iris. Sigma taunted him and asked him if he wanted to become a maverick again. Zero did not give in and defeated Sigma.

In the events of X5 Zero found himself to be powered by the Sigma Virus. As he was immune to the Sigma Virus perhaps him being the original carrier. Sigma stated that Wily told him about the Virus. Sigma also mentioned that he knew Zero had nightmares about Wily appearing in his dreams. Zero once again defeated Sigma with the help of X. However, as Sigma is defeated he fired one last shot severely wounding Zero.

Zero was strangely repaired and was discovered by X. X was glad to see his comrade alive. Together they defeated the Nightmare episode and Sigma.

Zero would team with X and Axle after the events of X6.

The elf wars emerged as elves were computer programs. Zero was sealed away for a while. However, he was discovered by Ciel. Ciel awakened Zero.

This stars the Z series. Ciel was trying to find another power source so reploids and humans could live together. However, Ciel and the resistance had to go against Arcadia and later Dr. Wiel who was ruling everything with an Iron fist.

Zero teamed with Ciel and defeated the Arcadia forces. He became a member of the resistance. Zero also stated his past events. When he encountered an impostor of X. He reminded the impostor of who X really was.

Zero was sadden when he saw the death of his longtime friend X. Zero started to question was it worth continuing the battle. Eventually he decided he would bring peace as that was his friend's dream.

He later lead the resistance against brutal dictator Dr. Wiel. Wiel had created a reploid named Omega based off of Zero. Still Zero was able to destroy this reploid.

In his last battle he was given a choice retreat and let Wiel escape or take out Wiel and burn up in the process. Zero killed Wiel but also sacrificed himself. His sacrificed finally brought peace among the humans and reploids.

Zero's personality is complex. He appears to be ruthless as he states I do not care what an enemy is if it stands before me I will destroy it. He never hesitates in battle. He is very powerful and he knows it. He also is intelligent developing strategies in the Zero series. He at times does not show emotion.

On the other hand, there are times when Zero does show emotion. He was concerned when he thought X had been wounded. He was very upset when he had to kill his girlfriend because of the Sigma Virus.

Zero though is a character that is tormented. Zero often feels guilty about the way things turned out. He knows he was the original carrier of the Sigma Virus. He also knows that when the Virus left him and entered Sigma it set the current events off. He also feels bad inside because Sigma has tried to use him to spread the virus which Sigma failed to do. Although he is tormented by this he does not show it.

Another thing that haunts the hero is him knowing his creator. Dr. Wily has appeared to zero several times in dreams. Zero knows he was created for destruction. In X5 as he though he was dying he started having flashbacks of Wily creating him and the virus. He states oh I see I was originally created for death and destruction I finally get the meaning. However, Zero did not die. Despite being in torment. Zero is seen as a great hero.

Capcom director at that time Kenji, who co-created Mega Man, in an interview stated that "Zero was intended to be a new hero. But he felt like he needed to create a new Mega Man character. So he created X. He wanted Zero to be a hero to so he game him a story of how he was a bad guy then turned into a great hero". (Kenji interview)