Infinite is the central antagonist of Sonic Forces and the main antagonist of its DLC prequel Episode Shadow. He is the Avatar's arch-nemesis and one of Sonic the Hedgehog's most dangerous enemies. He is a jackal who used to be called the "Ultimate Mercenary". After his encounter with and defeat at the hands of Shadow the Hedgehog, Infinite became obsessed with the desire to be the strongest until he is never defeated again. After Dr. Eggman enhanced him with the Phantom Ruby, he became the Eggman Empire's second-in-command who helped defeat Sonic and conquer most of the world.