Mavericks

Mavericks (マーヴェリック, Māverikku), is a term given to Reploids and Mechaniloids that are a threat to humans and other Reploids, which can be caused by errors, viruses, reprogramming, or even by their own free will upon deciding that humans are inferior and too weak to live (or some variation of this thought). They are usually countered by application of firepower to a certain degree in order to neutralize them. The Maverick Hunters were formed to enact this.

Maverick causes
There is no single cause for a Reploid to act as a Maverick, but generally a Maverick will fall into one of several categories.

Variations
There seems to be no single "Maverick Virus", but rather many similar viruses which produce the same basic effect.

The Maverick Virus
The original virus is simply called the Maverick Virus. This form causes the majority of Reploids to go Maverick, especially during the first 4 games. Its effect causes Reploids and Mechaniloids to go berserk and attack Reploids and humans indiscriminately. It was first discovered by a Reploid scientist, Dr. Doppler, who also created the first antivirus programs. It was later retroactivily renamed into the Sigma Virus, because Sigma became the most imfamous symbol for mavericks.

The Sigma Virus
The Sigma Virus is a modified form of Sigma's own DNA Soul and Dr. Wily's virus, created by the fusion between them. It is capable of infecting large numbers of Reploids and Mechaniloids alike, making them irrational and aggressive. Sigma has this virus spread across the Earth by network with the Central Main Computer to cause Maverick outbreaks everywhere and later to cause chaos and confusion in order to mask his true purpose: the Colony Virus. In the same game, the Sigma virus is displayed as a floating Sigma head, which when it touches X or Zero, will infect them. From onwards a new version of the Sigma Virus appeared, labeled as the Sigma Virus Mk.II. It is unknown if it is stronger or weaker comparred to the first version.

The Colony Virus
The Colony Virus was used to cause the failure and subsequent crash of the Space Colony Eurasia, hence its name. Little is actually revealed about this virus, except that when it came into contact with the Sigma Virus, the two merged and became the Zero Virus.

The Zero Virus
This is the virus which Sigma had hoped would "awaken" Zero to his "original purpose". If infected, Zero becomes much stronger and temporarily regains his lost memory, but otherwise retains his personality and memories. This virus form is more powerful than either the Sigma or Colony Viruses, and therefore, yields much more power. It appears after the fusion and will show a purple silhouette of Zero, rather than a head of Sigma.

As a side effect, it's appearance caused Cyber Space to materialise in the Real World at point 11F5646 as Rei Space.

The Nightmare Virus
This virus appeared in G1 Mega-Transformers X6. Gate, a researcher and primary antagonist in the game found a piece of Zero after he was destroyed. Using this piece, he reconstructed a virus and dubbed it the "Nightmare". This virus is odd because it actually takes a physical, destroyable form- a head possibly made to resemble a decaying Reploid, and a body made of tentacles resembling DNA strands, hinting at its DNA-based structure. This virus latches onto Reploids and infects them. When destroyed, it will drop a nightmare 'soul' which can be collected, but if it is left unchecked the virus will regenerate.

Other viruses
There are many other viruses in the Mega Man X storyline, but they all seem to share some commonality: they infect previously deceased Reploids and alter their capabilities significantly, but act more as a brainwashing or mind control tool than a cause of irrational aggression.

Free-will Mavericks
Some reploids are labeled Mavericks, because they have consciously decided, without any infection or flaw in their Suffering Circuits to go against the will of the humans. These are usually criminals, mercenaries or rebels who act against the government. Such free-willed Mavericks usually act more rationally than viral Mavericks.

A example of free-will Mavericks would be all of the new generation Reploids which came after Axl's creation. As Lumine reveals in Mega Man X8, they can go Maverick at will, because their copy chip contains Sigma's DNA and thus his way of thinking along with his philosophy of evolution - though technically, all Reploids in existence can potencially become free-willed Mavericks due to their ability to determine right and wrong for themselves, so new-generation Reploids are not the exception. Other examples include Vile, Shadow and the more extreme example of Colonel Redips, all ex-Maverick Hunters that turned evil to become more powerful - though Vile is questionable, as the reason behind his turn is an unrepairable break in his programming, like it was with the first mavericks, which were caused without any virus.

Another notable example of a free-will Maverick would be Boomer Kuwanger in Maverick Hunter X for the PlayStation Portable. The game manual states that Kuwanger sided with Sigma after looking over the facts rationally.

Problems caused by Mavericks
Mavericks present a large problem to the governments in the G1 Mega-Transformers X series. They actively fight against the governments and the Maverick Hunters, causing large amounts of collateral damage during their attacks.

Mavericks are usually the most destructive when they group together. This is usually hard for viral Mavericks to accomplish, but numerous times Sigma has been able to use them for his elaborate schemes against the Maverick Hunters.

Maverick Hunters
Due to the many problems posed by Mavericks, the Maverick Hunters were formed by Dr. Cain. The Hunters enlist Reploid soldiers to fight the Mavericks and perform rescue operations on their victims. On numerous occasions, this organization has stopped Maverick attacks on human cities, but it has also failed to prevent some large-scale damage, such as the destruction of Doppler Town, the Sky Lagoon, and the space colony Eurasia.

Mercenary groups
Also combating the Maverick threat are various mercenary groups, most notably the Red Alert (Syndicate) Syndicate (who became infected with the Sigma virus themselves) and solo mercenaries like Dynamo. The mercenaries and their organizations tend to be illegal and are also targeted by the Maverick Hunters. Some mercenaries have even been known to work for the Mavericks, making them all the more dangerous to the Hunters.