Nine was helping Sonic get the 5 shards so they could turn The Grim (a separate dimension) into their home. But when Nine figured out Sonic had different intentions, he took the shards and is going to turn The Grim into his home without Sonic. The Grim is a barren wasteland now, but with the shards power, Nine will try to change it. Nine has 2 tails and 7 tails made of metal which he uses to fight or climb.  Nine is able to harness the power of the shards and teleport to other dimensions. 