Searing pain ripped through my body as I felt myself being torn in two. My skin, muscles, and bones ripped, tore, and snapped as they broke apart and regrew. Then the pain stopped entirely, and I looked over at my other. He looked like me in every way. He looked at me and smiled. "It worked." he said. Our clothes had been ripped up i the split. Then a curious look crossed his face and his body slimmed up, his hips becoming more feminine.
I watched breasts grow on his chest and saw his penis squeeze into his crotch, being replaced by a woman's pussy. His brown hair grew out and cascaded down his back. Then he, now she, grew a couple of inches tall and seemed to age into her early 30's.
Then I felt odd and gasped as my world shot up. I saw what was coming and looked down to see a hairless, young body. I caught sight of my hairless penis and testicles just before they squeezed up into my own crotch, becoming the pre pubescent loins of a girl. I was a little girl. I snatched up the package the costume came in and looked closer at it. It was for a mother and daughter, the latter being meant to be between the ages of 6 and 8. I looked up at my other, now realizing he-she had just become my mother.
"Crap..." we both say at the same time.