Ron blinked and looked around. Why was he lying on the floor of his en suite? As he got up, holding the counter for support, he glanced into the mirror. He was still wearing Hermione's bikini. He hoped she wouldn't find out.
Looking into the mirror again, he did a double-take. He knew he had a bulge when he wore Hermione's underwear, but he cold have sworn it was in the bottoms; now, however, he had two perfectly shaped breasts to fill out the bra component of the bikini.
Puzzled, he felt them. They were definitely real; even his nipples felt extra sensitive. He rubbed them for a little bit, smiling to himself, expecting to feel some tension from the tight underwear as he got aroused.
His erection never came. Perplexed, he reached his hand down to his crotch and felt that there was nothing there. Feeling closer, he found an opening – he had a vagina! Where had that come from?
Ron decided to explore a bit more. He was experienced at pleasuring Hermione, so he knew exactly what he was looking for. Soon enough, he found his clitoris and started rubbing his finger back and forth.
It felt so good that Ron inserted another finger, almost doubling the pleasure. Rubbing himself more and more furiously, he eventually came, getting Hermione's swimsuit all wet.
Feeling a bit giddy, and wondering what Hermione had been doing all this time, Ron stripped the girl's swimsuit off and admired his new body in the mirror. Not really sure what to make of himself, he cast a cleaning charm on Hermione's bikini and made to grab his own clothes again, wondering how they'd fit.
But before he could even slip his own underwear back on, he collapsed onto the floor again.
On the other side of the locked bathroom door, Hermione was stirring. She slowly got up, using a bed post as something to lean on.
Feeling a bit cold, especially in the chest area, Hermione remembered that she was wearing Ron's swimming trunks. She looked down, and was surprised that she could see them without having to lean too far forward. Where had her breasts gone?
She was so worried about her disappearing breasts that it took her a few more seconds to realize that something else was amiss too – she had a bulge in her shorts.
Shocked, she slid her hand down to feel what was wrong and found something sticking out from where her vagina usually was. She grabbed it and gently tried to pull it out, causing it to stiffen. She gently pulled again and found that it felt quite nice.
As the object lengthened and hardened, she realized that she had grown a penis. How on Earth had that happened? She gave it another tug, giving in to the feeling.
Pushing the questions of what had happened and how to the back of her mind, Hermione continued to stroke her new genitals in the same way she had done to Ron many times before. No wonder he enjoyed it so much.
After a little while, the pleasure was too much for Hermione and she squirted semen all over her hands and the inside of Ron's shorts.
Sighing slightly in spite of herself, she wiped her hand on the outside of the trunks and slipped them off. For the first time, she looked down at her newly acquired penis. Noting how big she was, she cast the same cleaning charm on the shorts she had so recently been wearing.
Turning around to go get her own feminine clothes, she unexpectedly fell down again.