Shadow the Hedgehog is peak Sonic, he's always been peak Sonic, and after 23 years I can't bury the truth any longer
But it’s not evil for evil’s sake. Nor is Shadow really working for either Robotnik. His real goal is to avenge Maria Robotnik, who he was raised alongside on the orbital Space Colony ARK. While these events are expanded in later games, what we see in Sonic Adventure 2 through flashbacks are confusing and distressing.