After making his confession to Mary that he loved her female body, but couldn't stop thinking about what it was like to get fucked by her cock, when he was a girl and she was a man, thanks to the vials, John didn't dare refuse the potion which she sat before him, even though neither spoke to address what it was.
John was relieved to soon feel the by-then familiar sensation of his body shrinking, and slimming down, taking hold.
He moaned slightly, as he always did, and his skin softened, his hair lengthened; his boobs came in; and, finally, unseen in his pants, beneath the table, his scrotum receded into labia, his penis into a clitoris, and his vagina opened.
He was a girl again, for only the second time (that he knew of) in front of Mary.
Mary watched John transform with quiet fascination. When John was done, only then did John think about the fact that Mary had drank a potion as well, but he could not see how she had changed.
Mary wordlessly got up from the table, and walked around it, and began to caress the side of John's now soft face and neck.
That was when John saw the evident bulge in Mary's yoga pants.
"Uh huh," she smiled, kissing him. "Go ahead."
John stretched the elastic band of Mary's pants, and pulled them down, then hastily did the same to her panties.
There he saw it: Mary had an erection about 7 inches long in place of her clit, sticking out from the upper folds of her labia. Beneath it, she had no balls. She still had a pussy. She was still female. Or, perhaps, she was both male and female!
John had never felt more turned on ... he felt overwhelming desire for the female form of his hot wife, which he had always loved ... but also desired the meat of her cock to be firmly planted in his rapidly moistening cunt.
"I mixed the male and female potions together," Mary explained. "Don't you think this is a good solution to our dilemma?"
John didn't answer: his/her soft lips were already wrapping around Mary's dick. Mary moaned ... it was more sensitive than her cock had been when she fucked John as a man a few days ago ... but it wasn't quite as sensitive as her clit would be, at its most engorged. That would have been too sensitive for what they were about to do ....
They soon learned that without balls, Mary did not ejaculate from her dick, but had dry orgasms from which she was quickly able to recover. Without a word exchanged between them, Mary fucked John's pussy with her cock until they had to stop for fear of getting raw.
From then on, John was never a man at home. As soon as he got home, he would drink the female potion right after he changed his work clothes. In the morning, when he got up to go to work, he drank the male potion, so he wouldn't have to explain anything to his co-workers, or friends and family.
Mary drank the female/male every morning, and kept her cock pretty much all of the time. She tried to wear slightly looser clothing to hide it, but at the same time, she was aroused by the idea of someone occasionally side-eyeing her package. It turned her on to think about a man or a woman wondering what she had between her legs ....
Either due to their fascination with their changed bodies, or due to side-effects of the potions, both Mary and John were horny most of the time, and John became mostly submissive to Mary. In the evenings, and even through the night, Mary would take John's pussy whenever she wanted. Sometimes she would slap her ass in the kitchen, and they would start there. Other times in the shower. Sometimes in bed in the middle of the night. Sometimes even right before John took the morning male potion.
John didn't complain, and neither of them commented on how long it had been since John had a cock in Mary ....
After about a month, they decided to ...