Sidney has orange fur, a pink nose, and black eyes. He wears a brown jacket with a purple shirt underneath along with blue jeans and purple shoes.
Sidney was among the Emerald Hill Folk who left the Emerald Hill Zone to hide from Dr. Robotnik in the Mushroom Hill Zone. He would eventually be kidnapped by Dr. Zachary's Guardian Robots and hooked up to a biological computer, only to be saved by an electromagnetic pulse from Super Sonic.
After finding out Dr. Zachary had escaped, Sidney protested on behalf of his people against Knuckles the Echidna's attempt to chase Zachary, saying that, while they were grateful for all his help, they simply wanted to go back home. Convinced, Knuckles began preparing to lower the Floating Island down to Mobius so that Sidney and the other Emerald Hill Folk could return home.