Sonic The Hedgehog - Bloodline Connection

Fifteen years after Sonic Generations. Sonic and his friend have all grown up and either found their calling or had children. A particular case however is Sonic, head of the mobian defence force when eggman disappears without a trace. Sent a boy from his brother when Manic dies through a mysterious murder and is forced to take care of him on his own, too reluctant to hand over his brother's last gift to the world and send him away. He takes in the small hedgehog under his wing with the acceptance of all his friends.

Sonic soon learns though how evil and dark hearted this child can be.