Eventually, Rouge joins up with Doctor Robotnik and Shadow the Hedgehog, but it turns out that she is secretly working for ...

and inform Sonic what it is that Knuckles wants from him. Sonic Learns His Destiny As The Protector Of The Master Emerald Knuckles mentions that he's looking for something called the Master ...

Unlike Sonic, he possesses unique abilities, such as gliding and climbing walls, thanks to his spiked knuckles and powerful red echidna physiology. He is also the guardian of the Master Emerald ...