** I decided to play with a couple of my favourite tropes, Twin TFs and Feminizing diseases, the original version of this branch had several disease stories so this is my contribution to that proud tradition, please feel free to add to this**
Later, as he slept something interesting did , indeed, happen. Reality shifted so that an experimental virus got loose in the general population, it is rare, generally easily resisted but certain susceptible people can catch it and shortly afterwards transform in a surprising and incredible way.
Originally it was intended as a means to infiltrate terror cells or other secret criminal organisations, however the scientists bodged the job and it was abandoned. Environmental activists broke into the lab and accidentally freed the virus from it's containment, three of them became it's first victims and before they were contained the virus escaped. Once it was determined that only about 1 in ten million people are susceptible and that the results are mostly harmless, if not beneficial it was ignored.
The disease became known as Sexy Sister Twin Retroviral Syndrome or SSTRS, often colloquially referred to as Sisters Disease. The results are as follows; the original victim enters into Phase One, where he becomes receptive to someone else's DNA, during this phase he ( and it is always a he) will latch onto the DNA of any female within the age range of 15 - 45 and begin a process of copying that DNA onto their own genetic framework, during Phase Two their body will change into a physical copy of their donor, with certain differences, one, the copy is always female, even if the original donor is male, two the female is notably optimised for maximum beauty and sexiness within the genetic parameters of the donor.
Phase two is such a complete transformation that it included any genetic features of the donor, such as any congenital condition such as intelligence or disability, however any disability or intellectual impairment that occurred outside of a genetic condition is ignored, any genetic disorder that would impair their beauty or sexiness is ignored. For example if Jon were to become the twin of Tiffany Saunders then he would acquire her nymphomania and this might impair his grades due to being distracted, however if he became Sarah MacMillan's twin he would not automatically become a manipulative bitch as that is a function of nurture not nature.
Phase Three is when the donor is infected by a secondary version of the disease, they are optimised, and transformed into the identical female twin of their original selves, so if Jon got imprinted onto Karyn, she would become an even hotter version of herself after Jon became her Hot twin sister. There are few mental changes, so the victims personality remains basically the same, however there can be some mental changes over time as their brain is now female, they might be susceptible to certain genetic conditions which affect intelligence and similar biological reasons affecting personality. The victim and the donor also become psychically imprinted upon each other, they form a close emotional connection so that they become uncomfortable with being separate from each other for more distance than a few miles and more time than a few days, they prefer being very close to one another physically, this leads to emotional closeness, in some cases this can develop into full blown twincest, especially if the donor was someone outside of their original family and almost certainly if the victim becomes the twin of someone they were already in love with, this attraction is mutual. In any case the new twins will prefer to at least hold hands and go everywhere together. being separated leads to physical and mental distress.
Despite this slight downside many women, upon hearing of a male in a receptive state are tempted by the idea of getting someone who is their best friend and loving confidante for life as well as becoming optimised versions of themselves.
Jon has just entered the beginning stages of Phase one, he woke up aching all over, feeling dizzy and weak, his mom recognised what was wrong and placed a note on Jon's door warning everyone to stay out as he was in Phase One of SSTRS, she then informed the school. It did not take long for the rumour mill to spread news of Jon's condition and it reached the ears of certain girls who saw the opportunity that this represented, they plotted their next move.
Meanwhile at home Jon's mom Linda and his younger sister Zoe began to think of the possibilities.
Later that night as Jon was in a deep sleep a shadowy figure snuck into his room, they cuddled up to Jon and waited, after a few minutes they noticed Jon's hair growing a little longer , he had imprinted, soon his mysterious donor would have a new sister and they would both be beautiful and sexy, she could hardly wait.
The donor was......