As Sally took her pants off, Scott noticed the birthmark on her left leg and said "Wait a minute. You know I've seen that before but it never really occurred to me. Look at this." He pointed to his own and said "Come on, take a look. Compare it to yours."
Sally stopped and sat down. She looked at the mark and compared it to Scott's. The marks were really just reddish streaks, nothing dramatic looking at all, but they were exactly the same size and shape. "You're right," she said. "That's totally bizarre."
"Yeah," said Scott. "Twins aren't supposed to have the same birthmarks. Especially twins that aren't identical. How about fingerprints?"
"You mean hold my hand up to the light and compare it to yours?"
"Right, Sally, that's just what I was thinking." Sally held her hand under the desk lamp and Scott held his own hand nearby. He and Sally bent their heads towards the lamp to compare them. They could see the fingerprints and they really were absolutely identical.
"This is totally weird," said Sally. "It's not possible unless Dad's story was true. Do you know that old song? I am..."
"'I am you, and you are me, and we are we, and we are all together'." Scott laughed. "Do we still need to change to prove it works?"
"Of course!" said Sally. "I always thought it would be nice to be a boy for a while."
"Well, if this story is true, that's probably because you were one."
"Whatever. I want to try this."
"Well, most people would have to do this as a body swap, but we really don't have to. We're exactly the same except that you're a girl, so we can each change sex one at a time and we'll still turn into each other."
"I don't care," said Sally. "If you want to do it that way I have a bra I never used. Did you ever open those men's socks you got yesterday?"
"No, I didn't. Let me get them." He opened the drawer and gave Sally the package of socks and the medallion. She lay them down and stripped to her underwear, then tore open the plastic and touched the medallion to a sock. She put on the medallion and her form began to shift.
In a few minutes, she had become a male version of herself--which is to say an exact duplicate of Scott. Well, not quite exact; her hair, being short, was okay, but she had started with longer nails and she still had them. It wouldn't be too hard to cut them though. She looked funny wearing women's underwear, which she took off.
"Well, you can see me naked now. There's nothing you haven't seen already!"
Scott looked at his sister. It really was weird. "You're just like me!"
"Your clothes, Scott," she said.
"Oh." Scott stripped and handed Sally all his clothes in a bundle. When she tried them, hey fit perfectly, of course.
"Now," he said, "you'll have to show me your stuff." He looked out into the hallway. Neither his father nor stepmother were visible. "It's safe!" he exclaimed.
They rushed out into Sally's room, with Scott naked and carrying Sally's clothes. Sally (as Scott) found the unused bra and gave it and the medallion to Scott. He put it on and touched it to the bra. Soon his chest was expanding, his height was decreasing, his skin becoming a bit smoother, and his balls gave him the creepy feeling of trying to crawl inside his body, while his dick shrunk to almost nothing.
Scott then put on Sally's clothes. Needless to say, they fit perfectly too. Sally didn't like feminine clothing that much, and her jeans and shirt weren't really different from men's jeans, but it felt unnerving to wear the underwear.
"We did it," said Sally (with Scott's lower pitched voice, in Scott's body).
"I can see why Dad never told us the story before," said Scott (looking and sounding just like Sally).
After some quick wiping and use of lipstick, Sally (as Scott) opened their father's door and walked in. "You were right," he said. "It worked just like you said, Dad. Or should I call you Mom?"
"Dad. You know Vicki's like a mom, and you'd confuse people if you called me
'Mom'," said Scott Senior. "What did you use it for?"
"Oh, I tried Sally's old mittens but I took it off when my fingernails started to get long. And we compared our birthmarks and our fingerprints. I can't believe this. Magic... Can we keep this for a while?"
"You can't keep it for a while, but I'll let you borrow it for a while, if you keep it in the house," he said. "You know it can do much bigger changes than just your nails."
"I know," replied Sally (as Scott), "but we didn't want to try anything big at first. You did warn us."
Scott (as Sally) nodded, and they left.
So it did work. Scott was Sally and Sally was Scott. They had always been each other, in a way, and now they were literally each other and the older Scott didn't even notice.
"So what now?" asked Scott (as Sally).
Sally (as Scott) replied....
