Thus began Quatre's brief descent into madness. Overcome with grief, he used the resources of the colony and blueprints left by Instructor H to create the powerful Gundam Wing Zero. With the intention of destroying all weapons in space, he was entirely unprepared for the mental effects of Wing Zero's neural interface, the ZERO System. (The ZERO--or "Zoning and Emotional Range Omitted"--System is a system that interfaces a pilot's mind with a mobile suit's computer. It enables the pilot to become aware of the outcomes of possible courses of action. "However, due to this direct brain interface, as the human brain cannot process the raw data, the system will cause the pilot to vividly "hallucinate" the possible paths that the pilot can take; as the pilot tries to figure out what is going on, the system can overload the brain with too many statistics and estimated values, causing temporary insanity." Zero System, Gundam Wiki.) As a result of this, Quatre completely obliterated an OZ-occupied resource satellite and then went on to warn a nearby colony that he would destroy it, as well. The colony was evacuated, and Quatre went through with his threat.

Trowa, acting as an OZ soldier, and Heero, an OZ prisoner, were sent out to investigate the new Gundam, which was on its way to destroy a second colony. Certain that the pilot was Quatre, Trowa approached without caution, assuming that the five pilots would team up and fight OZ once more. However, Quatre warned him to stay back and ultimately shot Trowa's mobile suit with Wing Zero's buster rifle when Trowa didn't listen. The mobile suit took heavy damage; it was then that Trowa realized something was wrong.

Seeing Quatre as an enemy, Heero engaged him in battle. The two fought viciously, Quatre claiming that space had gone crazy and needed to be destroyed, and Heero claiming that any enemy of the colonies was an enemy of his. The battle went on like this, until Trowa intercepted a shot meant for Heero. The shock appeared to knock some sense into Quatre, and he listened as Trowa used his final minutes to get through to the other pilot, pleading Quatre to accept their place in the war and to return to the kind and gentle Quatre that he is, before his mobile suit exploded from its damages.



This event stayed with Quatre throughout the remainder of the series. He took Trowa's words to heart, maintaining that his friend had saved his soul, and felt extreme guilt over his own actions.

Afterward, Heero continued trying to engage Quatre in battle, but Quatre's mind had returned to normal, and he was more concerned with Trowa's apparent sacrifice than defending himself from Heero's attacks. Heero had already sustained injuries from the battle, however, and he soon lost consciousness, leaving Quatre to care for him.

Once Heero awoke, they were captured by OZ soldiers but soon released by members of the Treize Faction, a splinter group of OZ soldiers who were loyal to Treize. Unfortunately, OZ officer Trant Clark managed to corral them again and forced Heero to test the ZERO System. As expected, he was unprepared for its mental effects and suffered temporary insanity, much like Quatre, so with Trowa's words in mind, Quatre brought Heero back from the brink after yet another battle.

At this time, Quatre also had faith that Trowa was still alive somewhere, despite the fact that everyone insisted there was no way he could've survived the explosion; he remained desperately convinced of this, though, and throughout the next several episodes, it was something he was obviously preoccupied with.