When Earthrealm was young, Raiden was its protector. He fought the rogue Elder God Shinnok, who wished to rule it, in a war that threatened to destroy Earthrealm itself. One of the casualties of the war was the Saurian civilization (of which Reptile was a member), forcing the remaining survivors to emigrate to another world, which they named Zaterra. Some time later, Shang Tsung invited Raiden to participate in Mortal Kombat. Aware of the threat posed by this tournament to the future of Earthrealm, Raiden took the form of a human to compete.