... memories would be altered so that they would think that they had always been twins." The stone flashed, telling Jon that his wish had been granted.
And since the stone always tries to grant the wish with the least changes, when Jon looked into his mirror, he saw Joan. And since he wished that memories were altered, she thought that they had always been identical twins. Even though Joan heard the wish, it was forgotten.
Joan then thought that maybe she should let her sister know about the stone. She would of course tell her all the rules and to be very careful about what to wish. One mistake already make by Karen, her life long friend, should be more than enough of a warning to Zoe.
