Michael and Michelle were two siblings who shared everything. Whether it be toys or games, they would share it. This included secrets as well. SWAPP was no exception. "Hey, hey. Are you ready?" Michael asked. "Yeah. Stop asking... What do we do first?" Michelle replied. Just to mention, Michael is 15 years old and Michelle is 10. "First we have to take our clothes off and I'm gonna need your underwear." They did just that and Michael picked up the SWAPP. The two had seen each other naked before, it just seemed weird since they would be changing genders. Michael took the panties and put it on; his dick stuck out from its length. "Okay. Here goes nothing," Michael exclaimed as he drank the vial.
At first nothing happened. But then, Michael saw some of his dead skin fall from his head onto his visible dick. It was about to begin. Mike's dick hardened and elongated reaching 10 inches. He took the panties slightly off and started to jerk off like there was no tomorrow. Michelle just stared as she had seen this before. It was then that she started to feel her body warm up and something digging out of her vagina. Michael was finishing up as he ejaculated. His cum spraying feet from Michelle. "Here it comes," said Michael. "I know. I feel it too," Michelle replied back. The changes were to begin soon.
Mike's feet shrunk becoming daintier and sported red colored nails. Michelle's feet grew bigger and slightly hairier. His legs then shortened as the muscles went in. His skin was silky smooth and the panties fell down to his feet. Her legs grew and hair grew out. The muscles bulged as she felt them stretch. Then Mike's torso became smaller and his abs and pecs became non-existent. His pecs jutted out though into two small mounds that became breast. Michelle's torso grew and she felt abs start to form. Muscles everywhere as her breasts deflated and hard pecs came out. Then to the arms. His arms shrunk and all muscles became non-existent. His hands followed becoming dainty in the process. Her arms grew and muscles formed creating the same pain. The hands lost their daintiness and became meaty. On to the facial features as Michael's face changed shape, his eyes changed color. His hair grew out and turned blond. Michelle's face changed the same way. Her hair went back in and turned brown. It was almost over.
One last change was coming their way. Their genitals of course. First up was Michael. He felt as if his dick was being crushed. It got smaller and smaller by the second. His balls followed suit and lost its hair. It squeezed into his butt and his dick sucked in there too, became flat and formed a clit. Blood came out as that time of the month happened. Michelle must have hit puberty early. Next off was Michelle who's vagina was bugging her from the beginning and now she new why. She looked down to see something sticking out. A mushroom was what she thought at first. It bulged and pulsated and kept growing. Her dick came out like a serpent. It was big and meaty. Balls came out too and came out like fruit on a tree. Then came the strange part. Michelle felt a tremor like feeling come from her new member. It felt strange, yet oddly appealing. It didn't last soon as she erupted. The cum shot out and hit Michael as she covered it, getting her meaty hands. "Sorry," she said with her new male voice. "That's okay," Micheal replied with his new female voice. Seconds later the changes were complete and the siblings that share everything had one more thing to share.