After the stone flashed, Jon watched as his entire body changed. Within just seconds, he went from a teenage boy to a teenage girl. He wasn't overly sexy or anything like that. He was just a female version of himself, just like he had wished. In fact, he really only looked like a slightly older version of his sister Zoe, minus her gothic look.
She touched her belly, expecting it to expand. But it didn't. She grabbed the stone and made a wish to know why. Apparently, she had just become pregnant. So the baby hadn't yet formed inside her womb.
The stone also told her that she couldn't back out from being pregnant, because that would be a contradiction of the wish. She would have to remain pregnant until the baby was born. This was going to be a long nine months.
