Dan then had a weird idea: why not try drinking this stuff? He unscrewed the top and took a sniff... and was surprised how nice it smelled. Kinda like vanilla with a hint of something that was hard to describe, but if he were to try, he'd say it was sort of like pheromones. He took a sip, and it tasted even nicer, sweet and milky. He soon chugged the whole thing, gulping it down happily. Part of him was confused why he did it, but he liked it too much to really be that worried.
Soon afterwards, he started to feel strange- strange but good. He felt like his skin had softened, his body hair thinning, his muscles shivering as he rushed upstairs to look at himself in his bedroom mirror. He pulled off his T shirt and whimpered when it touched his chest, and he noticed that his nipples had perked up. He reached to touch one, noticing as he did that his arms and hands had become more petite as he did, and when he pinched it he let out an involuntary moan. Realizing he was forming new genitalia on his chest, he dropped his pants and began playing with himself eagerly, one hand jacking him off while the other pinched and rubbed his developing nipples. He watched as his chest enlarged, soft breast flesh emerging around his erect teats, his still mostly-male mind feeling as though his own body was a strip show.
To his surprise, when he orgasmed, he didn't shoot cum from his cock. He felt it pulsate, but instead his testicles pulsed and moved up into his body, and he moaned in an oddly high-pitched voice as he came. Then a strange feeling clicked inside of him- he felt his male desires shift into female ones. It was hard to describe the feeling, but something suddenly clicked in him, that he didn't want to have a penis to fuck with, but a vagina to be filled. His sexuality seemed to change too, as his fantasies shifted from beautiful girls with big boobs to handsome men with big packages. In response to these feelings, his body began to reconfigure his crotch to fit. His penis started to recede into its root, nerve endings accumulating in the head as it slowly reshaped itself into a clitoris. As his shaft shrank into a nub, his scrotum and perineum started to change, the line in between where his testicles had been starting to deepen, lips forming either side of it as a vaginal slit formed in his crotch. He felt his testicles, which had reshaped into ovaries, connect with his newly-formed womb, and it forged a vaginal passage inside him until the opening emerged at his crotch, making his body wholly feminine.
The last change came in his mind, as he... she... remembered her life as Danielle, her name in this body. She looked at her naked form in the mirror, surprised but impressed at how she looked. What would she do with it?