Jon looked in a mirror. There was one right there. He was shocked to see the face of his girlfriend Katie.
Of course, he thought. Unless there was some sort of ability to magically detect the stone, the stone would probably have been taken by someone he knows. He could... No, that was stupid. For all the trouble that his hasty wish had just caused, it did in fact reunite him with the real stone, even if in another body. All he had to do is ask. Jon, in Katie's body, picked up the real stone and made his wish. "I wish I knew how and why Katie switched the stone."
This wish worked a lot better than the last one and suddenly Jon understood the situation. The bitch! Katie only pretended to be interested in Jon to find out about his grandfather, who was involved in real magic--the real stone did come from Peru, but his grandfather had left some things out. He wasn't just a simple archeologist.
Switching the stone was easy. Just claim to be going to Jon's house to visit Jon, then pretend to leave while staying hidden. Once night falls, sneak in to Jon's room, take the stone, and wish yourself home.
There was one remaining question: why she had switched the stones instead of just taking Jon's stone and not replacing it with anything. That was a bad wish too; she had wished, in a fit of anger, to know how to find out what Jon knows. The Grail Stone told her to switch the stones and didn't give details, so she did. But now that all of this had happened, they had swapped. Katie was in Jon's body and Jon was in Katie's--but the Katie in Jon's body didn't hear the wish. So the change in reality changed her memories as well. Katie in Jon's body must think that she's Jon!
The glowing stone faded in Jon's hand. Nothing had happened. Of course it wouldn't, he thought. Why would anyone replace his stone rather than just take it? It must be some kind of prank. But on the other hand, the stone did glow. How could a prank do that?
Jon put the Grail Stone back down, as his anger changed to resignation. It was useless. What should he do next?
