If Sega were to give Sonic an actual, definitive backstory, what would you have in mind?

It seems that the general consensus(for the video game universe atleast) is that Sonic kind of just "appeared" on South Island one day. And an actual backstory(again,in the game universe atleast) hasn't really been touched on. I know it's said that he comes from Christmas Island but even with that,you only know the Island he came from. Not why he's so fast,not what made him become a hero or anything like that. What would you guys come up with if Sonic were to have a backstory?