...a little boy staring back.
The door burst open and Jon came in and grabbed the stone back from him. "Sean...don't ever touch this!! I'm serious...Now go down to dinner...we'll talk after..." he ran off to hide the stone.
The gods were against Sarah/Sean that day. Perhaps it was karma. He/she had stolen the stone from Jon. And now he'd have to wait through dinner as a little boy to try and talk Jon into undoing this.