Wechidna is a gooey alien that came to earth, and encountered a copy of Knuckles' Chaotix. He is tech smart, but has no understanding of human reasoning, so they act vicious when confronted, or don't understand what their motives are. They have a goal of reshaping whatever they find into their own image, with Knuckles' Chaotix being the beginning. They projected themselves into the game, and thus, Wechidna was born. He returned to Earth when Knuckles' Chaotix was still in it's development stage.