"... you were my twin sister forever and ever!"

Karyn laughed. Jon was aghast. "What have you done!?" "I ..." Karyn couldn't look her new twin sister in the eye. "I'm s-sorry, Jon." "You're *sorry!?* Gimme that rock!" Karyn complied. Jon held the stone in his/her clenched fist. "In this new reality, I *was* your twin sister. The stone can't change the *past,* which is stuck forever, thanks to *you,* but it *can* change the present. I don't have to *be* your twin sister anymore. I wish ..."