Scourge the Hedgehog

Scourge the Hedgehog or "Evil Sonic" is a version of Sonic the Hedgehog from an alternative universe known as Anti Mobius. Scourge's personality is the exact opposite of Sonic in all aspects, from his mistreatment of others to his selfishness and greed. Evil Sonic formerly looked identical to his Mobius-Prime self, until an interrupted encounter with the Master Emerald resulted in a permanent change of his appearance from blue to green, and two scars on his chest inflicted by Locke. Scourge is currently an operative of Dr. Finitevus and remains active in the prime universe.

The Anti Freedom Fighters
In the Anti Mobius universe, Evil Sonic along with Evil Sally threw their version of King Maximillian Acorn into the Zone of Silence, taking control of Mobotropolis and ruling it with an iron fist. Their only opposition was the kindly veterinarian Julian Kintobor whose units of SweepBots would clean up the litter left behind by the Anti Freedom Fighters. He would also take care of those who the Anti Freedom Fighters had inflicted pain on. (StH: #11, SSS: #10)

First Encounters
Scourge first (then known as Evil Sonic) encountered Sonic the Hedgehog from the prime universe while the latter took a detour through the Cosmic Interstate. After getting lost along the way, Sonic wound up in the Anti Mobius universe. The two briefly fought one another until Anti Robotnik helped Sonic apprehend his evil self. Sonic then continued his trip along the Cosmic Interstate back to Mobius. (StH: #11)

Evil Sonic later travelled to Mobius Prime, this time accompanied by Evil Sally, Evil Tails, Evil Rotor and Evil Antoine, all dressed like their Mobius-prime self. While Sonic, Tails and Antoine were absent in the Negative Reality trying to get to the Zone of Silence to rescue King Max, and Sally was occupied training theSubstitute Freedom Fighters, the gangs Evil counterparts began terrorizing the locals. Sonic and the others eventually showed up and confronted their evil selves, eventually sending them back to Anti Mobius. (StH: #24)