Marvis

A former member of the Mach Storm Team, Marvis used to be Helmut's best friend and Sigma's mentor. However, he had a falling out with the team, which caused him to go on a rampage; killing a member of the PKB. He was hunted down and captured by Helmut, and imprisoned. However, he was able to escape, and tried to get his revenge on Mach Storm. Marvis piloted a Shadow Fox.

Marvis is actually working for Alpha, and later ousts Gummie to become the chief of the PKB. After his Shadow Fox is destroyed, he gets a Styluarmor as a replacement. Furthermore, he proclaimed in the battle after his escape from jail that to him, his comrades, and the team were nothing more that stepping stones to become the most powerful Zi-Fighter. This proved true, even going as far as killing Graheme, Sandra's father, years before so his plans wouldn't be ruined. Because he inadvertently sent Sandra down the path of revenge (and in turn, though her own machinations, Blake), one could say Marvis is the catalyst for the rift of hatred between Mach Storm and Savage Hammer.

(Source: Wikipedia)