"As I was saying, I was always like this. As soon as I was able to talk I insisted that I was a boy. I didn't know anything about genitals so I didn't think there was anything strange about it... and for some reason my whole family went along with it. By the time I realized it was very unusual to have everyone call me a boy just because I say so, I had entered puberty. Then there was no question that everyone should call me a boy."
"You just said you're a girl."
"You know what I meant by that, Karyn. If a girl is someone with a monthly period, then I'm a girl. It's a matter of definition. But that's the only part of me that is a girl.
"Ahem," said Karyn. "You want to be 'filled'."
"Wanting to be 'filled' has to do with that part."
"Isn't it strange, having a part that's not your own?"
"No, it's not," said Jon. "My body is my body. It feels right to have mine just like it feels right for you to have yours. If people can't handle it that's something I have to deal with, it's not a reason why I'd want to change my body."
"Jon, we... I mean we might have had sex, but..."
"Yeah," said Jon. "This is embarrassing. I'd suggest using the dildo, but using it during my period would be a little messy. Karyn, you don't hate me for hiding this, do you?"
"I don't! But... I'm not a lesbian. I'm not bisexual. And it's not like I can say 'I wish I was bisexual' and turn into one by magic. I wouldn't want to do that even if I could, for the same reason that you don't want to change yourself. Maybe you should try kissing boys, Jon. Find out if you really like girls as much as boys. See how much you want to be 'filled'. And hey, if you get a boyfriend you two can kiss in front of me. It'll be hot."
"You mean that's it for us?" asked Jon.
"I don't know. I really don't know. Nobody chooses their orientation and I'm not sure ours are compatible. Maybe I'll wake up tomorrow and think 'if it's Jon it's okay'. Maybe I'm bisexual and I just haven't thought about it yet."
"Does that happen?"
"Do I look like I know anything about bisexuals? But if it doesn't, I hope we can still stay friends...."
The stone would stay gone, needless to say, until Jon's junior year in college, at which time it would exist, and he would remember it, but only his mother would remember that he's been transformed. But age 21 was still a long way off and lots of things could happen in his life....