Jon knew that there were a lot of people around--and the stone could have put him in the family of any one of them, within a pretty large radius. Comparing the number of people he knew to the number of people around, it would be a huge stroke of luck to end up anywhere he'd recognize--he was probably just in the family of a stranger.
Which meant it was really no use trying to check family pictures to see if there was anyone he knew. So instead he opened the door--which had a really disturbing boy band poster on it--and headed out.
The girl in the hallway was familiar--it was Sarah McMillan, not really one of the people he wanted to be around at the moment. Huge stroke of luck, huh? Jon wasn't sure whether it was good luck or bad luck. "Argh," he said.
"What?" said Sarah.
"Nothing," replied Jon. "I said 'argh'."
"Okay, Jon. Be that way."
"It's nothing I can explain, Sarah. Um, you are my sister, right?"
"Right, and you're my half-sister. In more ways than one."
"Then I'd be half your half-sister and half your half-brother."
"Don't get weird on me, Jon. It sounds like you've been hanging around Karyn too much. I mean, who ever asks their sister if she's their sister?"
"Nobody," said Jon and added "I wish you forget I said that."
Jon squinted as if because of an irritation in his eye, and Sarah responded "You want me to forget you said 'argh'?" This confused Jon briefly, but he realized that the wish did make Sarah forget he said all that--so all she remembers was the 'argh' immediately followed by him wishing she'd forget, with nothing inbetween. "Sure," continued Sarah. "Just don't forget that in a half hour from now...."