Shadow, like all of his species was part of an ancient breed of Zoids. An Organoid. He along with several others throughout the continent were located in a long abandoned ruin. It was the Helic Republic whom came across his stasis pod, and attempted to transport it back to a republic military base for further research. But, the convoy was attacked by a military patrol. In a desperate move, one soldier attempted to destroy the capsule rather than letting it fall into the enemy's hands, as they knew a single Organoid could tip the balance of power in unprecedented levels. But, the attempt failed. As a result, the black organoid was released, awoke, and took off leaving the Helic Republic troops at the mercy of the Empire.
For five years, the Organoid vanished into the wilderness of the continent until it was eventually captured by the Guylos Empire, and as a reward, was given to a young pilot named Raven whom gave him the name Shadow. For its life, Shadow would serve obediently next to Raven, adopting his cruel habits, and murderous tendencies.
Like Raven, Shadow would often relish combat against a powerful foe, and had no qualms about ripping into a Zoid to destroy it from the inside, even if there was a pilot inside. To him, all were enemies should his partner deem it.
Like all organoids, Shadow had the inherent ability to greatly increase the speed, defense, agility, and overall power of a zoid by an incredible margin. And with Raven's prowess in combat, this made the two incredibly deadly. But, his power did have its limits. For example, when dealing with an exceptionally powerful zoid such as the Geno Breaker, Shadow could only fuse with it for a certain amount of time and exceeding that could potentially kill the Organoid. Such was his fate during their final battle with Raven's all-time rival, Van Flyheight when a stray blast from a charged particle gun nearly melted the Geno Breaker. Shadow used the last of his energy to save Raven, only to die shortly after.