Sugar Skull, formerly known as Samantha, is Amy's evil sister from another dimension and a multidimensional traveler that kills Sonics from different dimensions. But do you know how she came to be? (No, I'm not talking about how she was born. Her parents already covered that.)
Coldsteel, the Hedgeheg (A Mobian that looks like a hedgehog but is also not), is a Mobian with a special power that he was born with. He's also a multidimensional traveler that kills Sonics from different dimensions. But do you know how he became a part of the Sonic Reapers?