The leader of the rogue military organisation called S.I.N. Formally the black-ops branch of G.U.N, that carried out most of its most secretive and controversial operations. Marcus Cain was the Chief of this department and thus, one of the highest ranking members of G.U.N as a whole. Also an important thing, he's had this role for a long time. When the order to raid the ark was ordered, which he heavily supported and pushed for. Once Shadow was imprisoned after the raid, Marcus secretly had some of his blood taken for privately funded research for himself, which would only be completed decades later. When this research was completed, the serum it created was injected into him, bringing back some of his youth, granting immortality and control over chaos energy similar to that of Shadow. After the events of SA2, the president of the United Federation with the aid of the evidence Rouge acquired during the whole debacle was able to grant Commander Tower the power and authority to clean G.U.N of most of its corrupt elements. S.I.N, facing termination and mass arrests, broke off and became an rogue independent organisation. Their ultimate goal is to usurp G.U.N as Mobius' prime security force, their idea of "security" being a far more authoritarian type, and to do so they use any means necessary. Terrorism, political subversion, destabilising various governments, etc.
