Jon's idea to create a device wasn't random, he had been up all night thinking about what he wanted to use the stone for and found his answer.
He wanted to spice up his life, escape the daily monotony and experience new things every day. That's why he wanted the device to be random.
Suddenly having heterochromia was neat and all, but now that he swapped reproductive organs with Karyn he's technically a girl, and that's a whole 'nother level of novelty.
Jon wants to keep the random swapping going, take some time between swaps to appreciate the changes, Jon was hoping Karyn would also want to keep trying new things. Yet Karyn instantly wanted to turn things back?
Jon thought about continuing to swap back and forth with Karyn, but it all that would do is slowly turn him into Karyn and turn Karyn into Jon. That would quickly loose it's novelty, Jon wanted to perform random swaps with other people too.
Still after seeing Karyn's reaction it was clear to Jon that he needed to rethink the device idea and tweak it. An easy fix would be to make it that only the person using the swap gun is aware of the changes; but seeing the other party's reaction is part of the fun. But people are likely to take notice of him using the gun and attempt to take it away from him, he needed a safeguard against that...
"I wish that only me and Karyn can recognize the device's existence. In other words that even if it's in front of them they don't see it, if they see someone using it they won't see the person doing anything out of the ordinary. They will however be able to recognize all of the swap gun's effects."
Jon paused satisfied with that solution when another problem came to mind. The device could swap anything even memories, what if it swapped out his memories of the stone and the device? Or what about swapping out his entire identity? Jon wasn't against his personality changing, in fact he was looking forward to it. But he still needed to retain some recollection of his old self in order to appreciate how he's mentally changed, same goes for Karyn. "I wish that neither I nor Karyn can loose our memories due to the swap gun and that we will be acutely aware of any changes to our personality".
Hearing his wishing Karyn pipes in: "What if we decide we don't like what we got as a result of a swap, shouldn't we have a reverse option?"
For a moment Jon was surprised that Karyn was able to criticize his idea, but then recalls that he only wished for her to play along with his ideas. She wasn't trying to stop him or convince him to not go through with the idea, she was actively participating in his plan by giving her opinion.
"No, that would undermine the point of it being random. If you could just cancel swaps until you got what you wanted, why not just make it so you can swap what you want in the first place."
"What if you couldn't choose what to cancel then? Like it cancels a random swap or maybe it cancels every swap for that day."
"No cause you could just spam revert until you're back to your original self, or cancel all swaps at the end of each day. Although..." Suddenly an idea started to take form in Jon's head.
"I wish that once a day the device let's you revert one change to a given target, but it doesn't apply to both parties involved in the swap. For example with this feature Karyn could get back her vagina and no longer have my penis, but I will keep my current copy of her vagina and not regrow a penis until I use the same feature to revert the swap on my end or get a penis from someone else in a new swap." "I wish that consecutive swaps need multiple reversions. IE if I swap Karyn's vagina for something else, reverting once will give me back Karyn's vagina, requiring me to revert again if I want my original penis back."
"You seem to focusing an awful lot on my vagina, anything you want to tell me?" Says Karyn jokingly. "But in all seriousness that does open new possibilities. Rather than a safety feature you've made reverting changes more of a game mechanic to play with in addition to random swaps."
"I'm only bringing it up because you were so fixated on having it back before."
"Well while thanks to your wish no matter how hard I try I can no longer bring myself to not want to play switcheroo with you... I'm still not comfortable having your penis between my legs nor you having my vagina, so I'll be switching those back. Though I haven't decided on which to change back first. Anyways are you almost done we're going to be late for school."
"Yes, yes. One more thing, actually two things since you're so now eager to swap around. First I wish that 24 hours after each swap or reversion reality will rewrite it's self as if that change was always how things were. Since a bunch of people freaking out about getting swapped would get old pretty fast. And second, I wish for a second identical device for Karyn to use.
