Ten long years have passed since Martha and Bella became mutants. Thanks to Martha's milk they were able to get off the streets and build a good life. They didn't get rich, but at least they weren't needy anymore. Their children, the eldest was Gia and the youngest Tommy, also grew up happy and healthy despite their mutant parents.
As the years passed, Gia had become a very beautiful high school girl, coveted by many boys at school. She liked to be courted and was openly bisexual, as she was also attracted to other girls. After all she never engaged in any sexual acts, she hadn't even masturbated yet. She didn't remember why, but her parents had started to take some precautions after becoming mutants and after she got older they told her that she should be very careful when starting her sex life, as her life would suffer a big change at this time.
One night Gia stayed overnight at her friend Freya's house, from which the parents would spend that night away.
Freya had recently broken up with her boyfriend, and before they went to sleep, she convinced Gia to help her experience what it would be like to have sex with another girl. They stood naked in the middle of the room, hugging each other as they fingered each other's pussy.
Once they reached orgasm Gia began to question why her parents told her to be careful if it felt so good. Freya was enjoying it too and the two girls hugged and kissed in preparation for round 2.
While they were kissing, Gia felt her tongue thicken and fill her friend's mouth more and more, which Freya was also surprised and pulled away to see what was happening and was shocked. Gia's tongue had become a dick and was getting hard.
Freya quickly tried to get rid of Gia, but she couldn't, because her breasts had merged with her friend's.
Finally remembering the important thing she had been forgetting, Fia started to cry and apologize to her friend "I'm so sorry Freya, I had forgotten. When I was a child I was infected by Mutation Liquid and I didn't become a mutant because of my age, but I thought at the time that I was safe and I ended up forgetting this detail. My parents always told me to be careful when I had my first orgasm, but I couldn't remember why. I'm sorry Freya, I didn't mean to involve you in this." she said as their bellies melted together.
"There's nothing else that can be done, I was the one who provoked you knowing that your parents are mutants. I thought they had gone through the treatment to not be infectious anymore." Freya said as their hips absorbed each other leaving them with, from a personal point of view, two butts, one in the front and one in the back, and they were fused in a way that they were forced to face each other.
"But we did the treatment. If I remember correctly, my brother and I also had the treatment at the time, so I can't infect anyone. If I remember correctly, my mother told me about someone she met while she was in quarantine who, during the transformation, ended up fusing with someone else who had not been infected. If it happened once then it could happen again and you ended up getting caught in my transformation." Gia said
Their legs fused together into a single expanse of highly strong, flexible flesh. For a while they even thought they were going to become some kind of lamia and were already expecting scales to appear on the 20-foot tail their legs had become. Then two huge pussies opened on opposite sides of their tail, their buttocks swelled and nipples appeared as they became breasts. Freya's mouth turned on her face, becoming vertical and, at the end that was up, a clitoris was formed, making her mouth a mixture of a mouth and a pussy. Lastly her two anuses expanded when a large cock came out of them and extended 13 inches.
"And now, what are we going to do? What will your parents think when they find out what happened to us?" Gia asked
"I think they will be very shocked. But what matters to me now is something else. We were preparing for round 2 weren't we?" Freya said and, holding her now bodymate's head, practically swallowed her cock-tongue with her pussy-mouth. They then advanced their hands down the practically permanent embrace between, them to caress the cocks that came out of their anuses and rose from between their breasts-buttocks. Eventually they reached their first shared orgasm.