Mary set the box down on the table and pressed the button. With a click the lid flipped back, revealing the rows of vials inside their felt lining. She looked over the different pictures on the labels curiously. They covered a wide range of things from animals to types of people (genders and ages). She had trouble deciding what to take first. There was one thing she had always been curious about. Perhaps everyone wondered what it was like to be the other gender once in a while, and Mary was no different. She located the vial she wanted in the case, one with an image of a man on it, right next to the vial with the image of a woman. She plucked out the vial and looked at it, the liquid was a vivid blue and as she uncorked it the faint smell of musk wafted up to her nostrils.
"Bottoms up." She murmured to herself as she tipped the vial back and emptied it into her mouth. She replaced the cork and put the vial back in its spot in the box. Right before her eyes the vial once more filled with the bright blue liquid.
Mary was soon distracted from the curious vials by a tingling itch that had begun to over take her entire body. This must actually be working, she had half expected it to be a prank, but now she felt something happening to her, hopefully it wasn't the onset of poisoning. Still she ran back to her bedroom where she had a full length mirror. She placed herself directly in front of the mirror but didn't see anything that seemed very different about herself. Except.. her shirt did look a little loose in the front. She quickly pulled it over her head and tossed it aside. Her bra wasn't as snug as it usually was, in fact, her breasts hardly filled them. She quickly removed it and was amazed once she actually saw them. She had been a C-cup, but now they were B's and quickly sliding backwards towards A's. Even her nipples seemed to be shrinking, the once half dollar sized nipples now maybe the size of quarters.
At this point her panties suddenly became horribly uncomfortable, making her remove her jeans and underwear. What she saw shocked her even more than her shrinking breasts. Sticking out from her shaved pubic mound was an inch of what looked like tiny cock. It really was working. She reached down to check her slit, only to find unbroken flesh where it had been. In fact near the front, right below the little shaft there was a spot of wrinkly skin that was actually sagging a little. It didn't take her long to figure out what it was, the start of a scrotum. She looked at it in the mirror, and saw it as it grew and hung even further beneath her tiny penis. Suddenly a spasm hit her midsection, and she felt her insides suddenly shift about. The empty scrotum suddenly plumped up as two testicles dropped down into them. In fact, they were a normal sized pair, or at least a normal sized pair from what she knew from her boyfriends over the years, it looked almost silly in combination with the small penis she was sporting. But she had to amend that, where it had only been an inch long before, she now sported two inches. And as she stared at it, it filled with blood becoming erect and pushing itself out to three inches. She was getting turned on by watching her own body change.
She looked back to her chest, where her breasts were loosing their last bit of roundness, leaving her chest as flat as it had been when she was eleven, her nipples shrunk to the size of pennies. When she looked herself over in the mirror, all sorts of little changes were noticeable all over her body. Her shoulders seemed to have gained a few inches in width, and she could swear the top of her head was closer to the top of the mirror that it was before. Her face had lost a certain femininity to it, her jaw more pronounced, her brow and nose a bit heavier. Even her black hair seemed shorter, before it had brushed her shoulders, now it was even with her chin and shortening as she watched.
But even as the hair on her head retreated, hair seemed to be appearing else where on her body. Her previously smooth pubic area now sported a small black bush around her now four inch penis. Her new scrotum was also growing a light covering of dark hair. Her shins and forearms looked darker, a bit of dark hair growing in there as well. There also seemed to be a slight shadow on her upper lip and chin. To her, she looked like a slightly underdeveloped teenage boy.
At first she thought her breasts were starting to grow back, but the shape was wrong, it took her only a moment to figure out it was muscle growing in, not breasts. In fact, everything on her seemed to be getting thicker. Her arms and legs were now half again as big as they were, and clearly had more muscle definition. Even as her slight pecs grew in, her stomach became more taught, revealing first a crease down the middle, then one across. It wasn't a six pack, but damned if it wasn't more than she had before. Her hands a feet looked bigger as well, her once thin delicate fingers were thick and heavy, they almost felt clumsy to her as she explored the changes to her body.
Sideburns were beginning to grow down the side of her face and down along her jaw, thin and sparse, but definitely a beard. The hair on her head was now short enough that her ears could be seen, but it wasn't stopping there, pulling itself back into a short slightly spiked cut. Her pubic hair now formed a thick triangle around what she guessed was a five incher, quickly moving towards six. Though a point of hair seemed to be growing from the top of her pubic bush, and even as she watched it continued to grow, meeting up with her belly button. Her shins were now dark with hair, as well as some of her lower thighs, and out of curiosity she lifted her arms to see the patches of dark hair under there as well. Her muscles were still growing as well, her limbs more than twice what they were on her feminine body, but on her growing frame it gave her a lean swimmers build. Not hugely muscular, but well defined. Her four pack had even become the six pack it hinted at.
The hair on her face continued to grow in, the stubble on her jaw meeting up with that on her chin. More growing in on her cheeks as that on her lip grew out to meet the rest. It looked the same as her boyfriend on weekends when he avoided shaving for a couple days. Even her brows looked thicker. There were dark hairs growing in around her nipples, and a bit in the middle of her chest as well. This was spreading out though, covering the bottom half of her pecs in a dusting of dark hair. The changes seemed to grind to a halt as a faint line of hair formed connecting her chest hair to her treasure trail. She ran her hand down along it until her hand met and wrapped around her still throbbing cock, now standing a very stiff seven inches. It had built up so much by this point that it only took a few strokes to make every muscle in her body suddenly stiffen as the orgasm went trough her. Her cock began to twitch as it spilled her first seed across the mirror and left her gasping for air.
Mary looked at herself once more in the cum splattered mirror. Or was it himself now. Definitely himself he decided as he looked over the lean athletic twenty five year old man in the mirror. He looked like what he guessed he probably look like if he actually had been born a male. He scratched at the stubble on his jaw, smiling to his reflection, and a rather hot guy he made too.
Mary, or perhaps Mark, he did like the name Mark, and it was close enough to Mary that he hopefully wouldn't get confused thought about what to do next, after cleaning up the mess across the mirror of course.