Originally, he was Unicron. He was once worshipped as the Sun God, Solaris, but Soleannan scientists split him into two, his body and his mind. His mind was then captured in a scepter and imprisoned while his body was imprisoned in the young Princess Elise as the Flames of Disaster. Eggman attacked Soleanna and caused a mess while Shadow inadvertently freed the mind, giving it a new body through his own Shadow. At that moment, the new creature became Mephiles the Dark. Mephiles briefly reunited with the Flames of Disaster after killing Sonic, but he was restored to life with the Chaos Emeralds and he, Shadow, and the first version of Silver took him down. His mind was still active after his defeat and he killed Silver when he went back to his ruined time. He then went on another time-travel journey and convinced his past to wait for the Transformers. They didn’t have long to wait before both Autobots and Decepticons started shooting at each other. He then entered the Matrix and made Optimus go mad and try to kill Megatron. He ended up dying and the Matrix was passed to Hot Rod, now Rodimus Prime. Rodimus, his version of Silver, and Megatron, now recreated as Galvatron, went back in time, unintentionally bringing Mephiles along for the ride. During the Battle of Station Square, he was given a body based on Hot Rod’s shape and reborn as Rodimus Unicronus. After a pair of setbacks, he saw his old self rise. Unfortunately, he would be the first Terrorcon to die as an upgraded Optimus took him down and killed him. He wasted away in Hell until the Author brought him back to life and offered to make him a god of a new multiverse. Anything to finally get rid of Optimus Prime!