“SONIC... D-DEAD OR ALIVE... IS MINE.”

This is Metal Sonic, which is Dr.Eggman’s best and most powerful robot that he’s ever produced, and seemingly the only one that’s survived that other fake hedgehog’s rampage.

With Eggman and everyone else dead, he alongside you are the only one who’s alive right now, and have to survive against 2011X in X’s Castle.

Despite Metal Sonic once being a villain, he was programmed to actually protect anyone, especially the last survivor, which just so happened to be you.