He was a Maximal experiment, trying to recreate Starscream's indestructible spark. It was a success, however Rampage turned out to be a powerful murderer. He went on a killing spree until he was stopped by Depth Charge, and he was stored in stasis aboard the Maximal exploration ship that Primal captained. Their mission was to eject him into a sun but they attempted to intercept the Predacons. When they were crashing, Primal had all the crew members in stasis shot into orbit so they'd survive the crash, but he inadvertently ejected Rampage too. When Rampage landed on Earth, both the Maximals and Predacons raced to retrieve him. Megatron II succeeded on procurring him, and by taking half of Rampage's spark, was able to keep him under control... that didn't stop several attempts by Rampage to kill him, and even more thoughts about it. He was apparantly finally killed by Depth Charge when he rammed a large spike of raw energon into Rampage's spark.
Rampage was incredibly sadistic and antagonizing to his enemies (especially Depth Charge), often enjoying destruction. He seemed to lack any remorse or mercy towards anyone until he met Transmutate, whose destruction left him devastated. He deeply despised Megatron when the Predacon leader took a part of Rampage's spark to keep him in line as leverage if Rampage would try anything.