An enigma to all who come in contact with him, ermac's past remains shrouded in mystery. it's believed that he exists as a life force brought together by the souls of extinguist outworld warriors.
Shao Kahn has managed to take posession of these souls, and use them to fight on the side of tyranny during his invasion. But these souls within him didn't thrust their evil master, Shao Kahn. But Ermac stays on the side of the outworld emperor, planning to take over his power as soon as he defeated the chosen warriors.
After of the formation of the Deadly Alliance between Shang Tsung and Quan Chi, Ermac met with Kenshi who was stranded in outworld. Kenshi sympathized with the plight of the enigmatic kombatant, Ermac. The Outworld warrior spirits that manifested themselves in the form of a ninja had been violated by Shao Kahn in much the same way that Kenshi's ancestors had been enslaved by Shang Tsung. Kenshi was taught the Telekinetic Slam by Ermac in return for freeing him from the control of the Emperor. Little did they know that the Deadly Alliance was on it's way to end Kahn's rule... and life.
Actully Ermac was a Reptile MK1 Arcade Glitch. Here is the Story, Sometimes a player would unlock the Secret Fight to take place in the Pit With Reptile, Very Rarely Reptile would Apear Orange, and his energy bar Read "ERMAC" Witch means Error Macro.