While chasing after a rebel, Zechs caught up with the man on the Darlian estate, only to find that the hostage that he had was none other than his younger sister, Princess Relena. After saving her from the terrorist, he calls her a princess. When she asks whom he is, he tells her he is a Prince of the Stars.

His first encounter with Heero Yuy is chasing the pod that Wing was enclosed in to Earth, near the JAP point of Earth. After seeing that he was not going to win with conventional methods, Zechs escaped his Leo Mobile Suit and set it to self-destruct. Thinking that it had blown up, he left both the suit and pilot be for the moment. A short while later, Zechs and Heero agree to have a battle in Antarctica to end their feud, and are interrupted by Relena. 

Noin tells Relena that Zechs is her brother and should not wish for the death of her only family. The girl is confused, and the battle is further stalled by the arrival of Alliance suits. Zechs allows the injured Heero and Trowa to escape, as well as Relena and Noin by serving as a distraction. He then proclaims that if his mask breaks in battle, then he and Treize can no longer be friends. Unfortunately, it breaks and we don't see Zechs for a while.

Some time later, he reappears with the thought lost Wing Zero and as the leader of a group called White Fang. He, and the group, hold Earth responsible for all the loss of life during the pointless war and decide to use the space base, known as Libra, to put an end to the madness. They plan on blowing a hole in the middle of the Earth, thus eliminating the threat it poses.

Heero shows up, yet again, and they battle once more. Somewhere in the middle of their fight, the two switch Gundams, and Zechs is now in possession of the infamous Epyon, built by none other than Treize. He eventually becomes to own the Tallgeese III, an even better and deadly mobile suit than either Epyon or Tallgeese II that came before it. He loses his battles with Heero once again and disappears into oblivion.

When the Mariemaia Army threatens to take over the newly unified Earth Sphere, Zechs reemerges to help his old ally, Une, keep the peace on Earth. He is rejoined by Noin, and they keep the fighting to a minimum as the Gundam Pilots show up, shedding no blood of the enemy. When peace is once again saved by the Gundam pilots, *and* the civilians around, Zechs heads off to Mars, joined by Noin - who has vowed to never leave his side again.