It was that moment when Jon arrived. He had heard the insult-reversing wish, and could easily figure out that the dog in Sarah's clothes was supposed to be Sarah.
On the other hand, he hadn't heard any of the wishes Sarah had made on Karyn. So Jon believed that things were always like that. As far as everyone else was concerned, Sarah had not wished that Karyn stay in that area or that Karyn obey her orders. Rather, that was what it had always been like.
Picking up the rock, Jon wondered. What had Sarah done? Somehow she had managed to get hold of the rock and insult someone. Maybe even Karyn. As far as Jon could remember, this strange girl named Karyn had always stayed in that area. He had even talked to Mr. Philips, the science teacher, who had been around for decades... and Mr. Philips reported that 20 years ago, the girl was already there. She never talked and just wandered or stood still--except, somehow, Sarah had gained the ability to order her around and have the orders obeyed.
Jon occasionally felt sorry for the strange girl. Within her limited domain, she was human... it was obvious. Yet Sarah had always treated her like a thing. Ordered her around, until one day--today!--she overreached herself. The wish that Jon had made about insults must have rebounded--Sarah called someone a bitch and turned into one instead. (In a new reality where Karyn had always stayed in the area, Karyn probably wouldn't have had the stone or made the insult wish, so Jon remembered making it instead.)
Jon picked up his stone....
