Sammy is one of two characters who used to live in the Hidden Zone on Mobius. A panda and a hippopotamus one day noticed a "shooting star" heading to their location, before discovering it was the "super cool hedgehog" Sonic the Hedgehog! The reason why it isn't clear which of the two is actually Sammy is because they call each other it. There is a possibility that they are both called Sammy, but it is more likely an error by writer Mark Millar or letterer Ellie de Ville.
Either way, the pair took Sonic to see Zone Leader Steve Owl before they were attacked by a squadron of Badniks. After the invasion, Sonic led them to the safety of the Emerald Hill Zone, effectively becoming part of the Emerald Hill folk.