- You may be looking for the Sonia Acorn from Light Mobius, or Sonia the Hedgehog from the Sonic Underground Zone.
Sonia Acorn is the daughter of Queen Sally and King Sonic in a future dimension of Mobius. She was seen to be happily playing with her grandfather Maximillian Acorn with her brother Manik. She and her family had a brief encounter with Robotnik Prime when he was inadvertently transported to that universe by E.V.E., saying he looked "mean and nasty". Sonia was tragically killed along with the rest of her family when Robo-Robotnik nuked the planet. (StH: #22, #75, IYF)