Scourge the Hedgehog did not originate from fanon, and the information on this page may not be entirely accurate to their canon. You may read more about this subject in the context of their canon on the following wiki(s):
In a parallel version of the Sonicverse, known as Anti-Mobius (or more often, Moebius), Scourge managed to steal a Chaos Emerald and teleported to Mobius, the prime parallel to Moebius. He made his way to Angel Island for the Master Emerald and absorbed the energy, transforming him;, his fur turned green and his eyes turned blue, permanently, Even though he no longer needed to be here any more, he quickly realised he couldn't get back. Knuckles' father, Locke punched him in the chest leaving two huge scars across there, he vowed revenge, and wanted to find the real Sonic.
Scourge makes an appearance in Sonic Heroes 2. In this game, his animal instinct is much more portrayed than on any other occasion; the very start of Team Sonic shows Scourge sneaking into Angel Island. He is about to lift the Master Emerald when suddenly it detonates and Scourge bolts. He lands up in Great Turquoise Zone. It is here that Scourge's and SSS's aims are shared and they join forces.