Sonic defeated Dr. Eggman only to find that his best buddy Tails had not survived. After the credits rolled, he returned to Eggman's abandoned base to find the young kit's body gaunt and lifeless, locked up dungeon-style in a room Tails would never again see the outside of. Sonic was crushed with sorrow; he would never again hear the cute kid's annoying voice or watch him go to town on one of his machines, and all because Sonic, for the first time, hadn't been good enough. Tails was gone.
Or was he? Sonic recalled talks with one Amy Rose, whom he had saved from the Dr.'s and the dastardly Metal Sonic's claws only months earlier. She still owed him a favor, though she would have preferred to pay Sonic back in close, sweaty embrace under the stars on the meadow overlooking Never Lake, with robots peeking, terrified but curious, over her discarded dress. Sonic had different plans, at least for now: Amy had boasted of proficiency with tarot cards. He was not well-versed in the extent of these strange items' power, but he could darn well give her a shot.
Amy was horrified at what had happened to Tails, though she could not come close to finding it in herself to blame Sonic, and she accepted immediately his request for help. She laid out the cards corresponding to time-reversal and two otters holding onto each other for dear life during a tumultuous monsoon, then whispered her trusty incantation. The two hedgehogs found each other whirling through an incorporeal tunnel into a past with a living Tails. Amy took the helm and showed Dr. Eggman the meaning of "taking a pounding" while Sonic scurried ahead and scooped up his best buddy. When the two boys returned, Amy hugged them tightly.
All was not well, however. Amy's magic had been more potent than she had planned, and in an instant, time jumped backward again. She was in the arms of a blue hedgehog, but not the one she wanted: Metal Sonic had recollected her... or had he only collected her for the first time? As Sonic approached, Amy had the sinking feeling that he barely knew who she was, and that the same was true of her.
Another skip, and they were separated for good. Sonic and Tails were on an adventure of their own, finding themselves first in a garishly-colored factory with odd liquids filling up large swaths of it. Amy, however, was at home with her parents over breakfast, telling them excitedly about the dream she had had involving a blue savior. The two older pink hedgehogs chuckled in some confusion - but, to be sure, also in great love of their daughter and her storytelling abilities. She was sure it was more than just a dream, though. It had to be.
One more skip, and Sonic was on his own. He had the unpleasant sensation of having been sad through the loss of something close to him - and, more recently, two somethings close to him - but he just could not remember. Ah, it didn't matter; Eggman had to be defeated so peace could return to Green Hill. Amy was taking a bath and felt too the loss of something, but only for a second. She then returned to shampooing her hair and playfully dunking it all beneath the water. No hedgehogs were afraid of a little water, of course, not as far as she knew.