Board Thread:General Discussion/@comment-71.167.167.158-20160723171500/@comment-109.66.21.226-20160723205639

He was not the original One Eyed King. He was groomed to be one by Eto and Arima. Technically, there is no such thing as a One Eyed King. Its a term that was coined by Eto for a strong individual that is undefeated, which is Arima Kishou. That's why Eto and Arima both made a secret pact to find a ghoul that will be capable of defeating Arima Kishou.

Essentially, Arima Kishou did not know that he was the One Eyed King, which Eto considered him to be one. Only after his death, Eto revealed the truth to Ken Kaneki and left him with the option of deciding whether he wants it or not. Eto has been waiting for a strong ghoul to show up and unite the rest of the ghouls, hence destructing the current world order and create a new one.