Fusion Shadow takes the appearance that of a, well, Fusion copy of Shadow. The eyes are completly red and Shadow's black fur is replaced with green Fusion parts, though Shadow's red streaks are still intact. Shadow inhabitor rings are still worn by Fusion Shadow, but have turned red instead of remining gold. And Shadow's white chest fur, muzzle, ear skin, the red part of his gloves, and shoe soles have all turned into stone.
Not much is known on how long Aku's been under Fusion Shadow's command, or how Fusion Shadow caught Aku. Aku was seen guarding the Comet durring Sabir's first arrival to the bad future.
Scar has been under Fusion Shadow's command since he was eight years old. His efforts of trying to fight off the Fusion Arms after his parents died turned into his capture and inslavement. After several years of training, Scar's first mission was to spy on the R.A.F.A. resistance group untill Fusion Shadow invades their base.