"I wish for the list of items I'm thinking of."
A large cardboard box appeared in front of her. "That's good!" said the girl and she put the stone down and picked up the box. He could see various things in the open top: clothes, makeup, a stack of gift cards held together by a rubber band.
"I hope you got everything you wanted," said the boy.
"I have to. But I need to go unpack," she said. She carried the box out of the room, leaving her brother to close the door.
The boy picked up the stone and thought. That was a close one. His sister... well, the way he did that wish, he didn't make a sister. He became the brother and sister. They were both equally Jon; just because he was the only one who knew he was Jon didn't make him the "original". If he got amnesia and thought he was a girl, he probably would wish for a box of girl stuff too.
"I wish I knew my sister's name." Then he got suddenly suspicious and added "No..." That 'no' was useless, but didn't hurt this time. "I wish I knew both our names."
Instantly, he knew. He was named Jason and his sister was named Jane. Of course... since neither was more original than the other there was no need for one to have the original name. He supposed he could wish his name was Jon, but he didn't. Instead, his next wish was... "I wish I knew enough things about both our lives so as not to seem strange or forgetful."
Basically, instead of Jon growing up as one person, Jason and Jane grew up as twins. Jon's friends were now the friends of Jason and Jane, sometimes of only one, and there were a couple of new friends that only Jane knew. Some of the things they did in the past were shared by both of them; some others were split between the two of them. Jon had had two accidents in chemistry class; in this reality Jason had one and Jane had the other. Jason and Jane had both gotten the stone; Jason demonstrated the blue tree branch and Jane demonstrated that it could be made darker.
So everything was working as he had expected. Except that Jason might want to take some precautions. His new memories revealed that Jane wasn't too bad a person, and he could probably trust her not to make nasty wishes, but there was no way to be sure. And there was one other thing... He really hoped Jane hadn't noticed that erection.
