As a PlaneswalkerEdit
Travelled to Origin Earth along with, or summoning rats to help him out in his conquest and murderous rampage. His exact motivation is unknown, but he did appear to want the Gongshow:Gaiden crew dead or captured. While the killing blow was performed by Chris "Topher" , the greatest part of the damage was done by Deekin.
The Rat King was a pretty strange guy, even by TMNT standards. We never really learned from the cartoon just why he was the way he was, but he obviously had some major psychological problems. A sewer-dwelling human who seemed to be convinced that he was a particularly large and powerful rat, and he even seemed to have developed a rapport of sorts with genuine rodents, capable of communicating with and even controlling them. Seriously disturbed.