"This can't be happening," Jon said in shock. He specifically said that he himself couldn't be affected, yet he was changing right before his eyes, becoming a little more like Zoe, as Zoe became a little more like him.
What Jon didn't understand and probably wouldn't understand, at least for a while, was that he was dreaming. He never even made his wish. In fact, he never made any of his wishes, since he entered the bathroom. Someone was waiting for him there: a witch who wanted the stone. Upon his arrival, she cast a sleeping spell on him, causing him to fall into a very realitic dream-state. Of course, since it was a dream, there were no rules for or limitations of the wishing stone. And that's why his wish was affecting him too, even though he excluded himself in the wish.
The witch looked down at the sleeping Jon, who was trapped in a seemingly never-ending dream. Then she looked at the wishing stone in her hand and smiled.
Such power, and it was all hers.