This is going to explain my headcanons on what goes on in Shadow's head during the events of my Shadow Saga Series. I'm not a professional but this is what I think.

The prequel to the Shadow Saga Series, detailing the events from Maria's birth and diagnosis to Shadow's creation.

All Shadow wants is to fulfill his chosen purpose and heal his surrogate sister, Maria Robotnik, so she may one day return to the planet she loves so much. But as the ARK grows more and more dangerous day by day, and as his creator grows more and more afraid of the government's plans, Shadow must face the reality that the world he has been born into is a twisted one that will do anything to take him from his home.

Shadow believed he'd been left to rot in stasis for fifty years, but he never imagined that the descendant of the one who created him would be the person who freed him from his prison. Once again released into the world, Shadow sets in motion a plan to destroy all of humanity, but he's going to need some help. Alliances are formed, ties are tested, and even his very existence is questioned. All of this, in an effort to fulfill a promise he made to a sick little girl...

Pre-Sonic Heroes. Sonic reflects on life after Shadow's sacrifice, expressing his regret that he was unable to save him. Meanwhile, Eggman makes a peculiar discovery.

Shadow survives the fall from the ARK, but has lost his memories in the process. After being put in stasis a second time by Eggman, he is found prematurely by Rouge the Bat, and a new team is formed as a journey to find and question the "good doctor" begins. Is Shadow the same person as the one Rouge knows? Or is he just a copy of the real Shadow? And what's going on with the strange things Eggman has been saying?

Post-Sonic Heroes, pre-Sonic Battle. Shadow has learned to depend on and live with Rouge, but Omega is another story. Still not trusting the robot, his doubts only increase when he learns that Omega's been sneaking out at night. Shadow decides to follow him, but what he discovers changes his mind about the robot's existence.

Shadow is still unsure about his purpose, but he has very hazy memories of someone named "Maria", a person who has been lost to him somehow. When the voices in his head turn out to be real, he finds himself on a mission to hunt down and destroy the resurrected Gizoid, an ancient weapon with enough power to annihilate the entire planet. The problem? The Gizoid is in the hands of Sonic the Hedgehog and his friends, who swear that "Emerl" (as they call him) is one of them, not a weapon of war. Shadow is dead set on proving them wrong, but maybe he's overthinking the fact that he himself has unimaginable potential...