Of all the Gundams out there, few are as twisted and dark as the infamous JDG-00X Devil Gundam, the Ultimate Gundam of the anime Mobile Fighter G Gundam. In a series filled with windmill Gundams and Burning Fingers, the Devil Gundam is by far the strangest and scariest of them all.
To understand just how twisted this bio-organic sentient mobile suit is, one must investigate its myriad of dark secrets, from the cancerous virus that emerges from its bulk to how it devours and merges with floating colonies in space to how its primary goal is the eradication of humanity to save nature.
The Devil Gundam Was Designed to Self-Improve (and Thus Became Evil)
The Devil Gundam was originally created as the Ultimate Gundam by Dr. Kashuu -- the father of G Gundam's protagonist Domon Kashuu. Dr. Kashuu's philosophy when creating this all-powerful Gundam was to create a machine that could self-recover, self-replicate and self-evolve. While the other two aspects would result in some truly grotesque situations, the evolution aspect in particular led the Ultimate Gundam to become the Devil Gundam.
Dr. Kashuu made the Ultimate Gundam to improve the planet Earth. In G Gundam, Earth has become a battleground for the Gundam Fights -- tournaments held every four years to determine which country will rule the planet. As a result of the fights, the planet has become entirely ravaged, and most of humanity has moved into floating colonies in orbit around the Earth.
When the Ultimate Gundam crash-landed on Earth, it achieved sentience. Through its observations, it realized that nature's biggest threat was humanity. Ergo, it would have to eradicate humanity entirely in order to save the planet, so it evolved to be perfectly suited to end the human race.
The Devil Gundam Can Regenerate -- Imperfectly
When Dr. Kashuu unveiled the Ultimate Gundam, the Japanese military, led by Major Ulube Ishikawa, tried to steal it. Dr. Kashuu's son Kyoji took command of the Gundam and steered it away, only for it to burn up in Earth's atmosphere and become almost entirely ravaged. However, the Ultimate Gundam could regenerate.
Unfortunately, the regeneration process was imperfect by its nature. While its body could physically regenerate, its programming was scrambled and distorted upon re-entry. This contributed to the Devil Gundam seeing humanity as a threat, only spurring on its evolution into the destroyer of the human race. Had the Devil Gundam's regenerative abilities been more complete, it might never have turned into an ultimate killing machine.
The Devil Gundam Requires Human Life to Function -- Mostly Women
The Devil Gundam requires a human power source in order to function. Ryoji initially served as its primary host, though that energy source proved to be less efficient as time went on. Master Asia attempted to make Domon, the strongest Gundam Fighter on the planet, into the host in order to coopt the Devil Gundam against humanity.
However, as Major Ulube ultimately determines and capitalizes on, the Devil Gundam tends to prefer women for its power supply. Due to the Devil Gundam's self-replicating powers, women who are able to give birth allow it to tap into its mass regenerative abilities. When the Devil Gundam had Domon's lover Rain as its power source, the Devil Gundam gained the ability to overtake the Colony of Japan, transforming into the gargantuan Colony Devil Gundam.
The Devil Gundam Can Give Birth to New Gundams -- Or a Nanomachine Virus
The Devil Gundam's self-replication ability can take on two grotesque forms. It can either produce entire Gundams from within its body or produce a nanomachine virus that spreads via contact. The Death Army is an armada of self-created Gundam suits that fight in the steed of the Devil Gundam, relaying information to the core unit. The Devil Gundam in its colony form can create an army large enough to combat the world's force of Gundam Fighters. Among his more iconic creations are the Four Heavenly Kings, four extremely powerful Gundam Fighters that partook in the Gundam Fight against Domon and his companions.
The DG Cells are even more insidious. DG Cells are nanomachines that overtake a human being. Signs of DG Cell infestation include hexagonal blotches that spread over the skin. DG Cells can cause Gundams to self-improve and become far more powerful. If DG Cells infect a human being, they too gain unique abilities, such as increased vitality, strength and even regenerative abilities. However, these gifts come at the cost of having their will and desires overridden by the Devil Gundam itself.
The Devil Gundam Can Bring People Back From the Dead as Zombies
The Devil Gundam can restore the dead back to life -- in a manner of speaking. Ryoji uses the Devil Gundam to create a clone of the deceased Schwarz Bruder using DG Cells. However, this Schwarz, perhaps due to Ryoji being the pour source of the Devil Gundam, managed to resist being controlled by the Devil Gundam's will. This is one example of the Devil Gundam cloning another dead human being.
However, it can also actually restore the dead and bring them to life. Such is the case with Gentle Chapman, Neo-Britain's legendary Gundam Fighter. Chapman had previously been killed in action against Domon Kashuu, dying thanks to the mental stimulants that kept him active after surviving so many prior Gundam Fights. However, his corpse was found by the Devil Gundam and infused with DG Cells.
Rather than coming back to life like Schwarz, Chapman returned as a mindless slave, piloting his Grand Gundam under the Devil Gundam's control. Ultimately, Chapman was obliterated entirely from within his cockpit, but that did not change that the DG Cells inside of him propped up his corpse, reanimating him as a zombie under the Devil Gundam's genocidal will.