Sonii the Hedgehog

Sonii the Hedgehog is the sister and of Sonic the Hedgehog and a version of Sonic in Blaze the Cat's world.

History
In Sonii's Alternate Universe, shes basically Sonic's twin sister, but the bad part of her universe, is somehow he gets warped out of it, and now it was up to her to take care of Earth until the two somehow reunite which is sometime after Sonic met Emerl. Basically taking his place in the timeline through the future.