((( NOTE: I don't own any harry potter, also this story was on Choose your own change, but was removed in 2009, so i thought to post it here, also i will be adding more that what was posted before**, All characters in this story are at least 18 years old)**

Harry's nose twitched as the first hint of the smell hit him.

Ron smelt it next, "Oh my God", he explained, "What is that stink? It smells like there is a very horny goat in here."

"I think it's me", said Harry. "It's coming from...from my crotch!"

"Bloody Hell", Ron screwed up his nose as he spoke, "This has to be someone's idea of a magical joke. This is just sick. Who the hell would come up with something like this? Oh my God, you'll have to see if you can remove that stink with a shower or if you'll need some sort of spell to get rid of it. I'm not hanging around to see how you get on."

With that Ron left the common room. Neither Ron nor Harry had noticed the effect of the stench on Hermione. She was taking deep breathes of the stench, her breathing getting heavier as the smell began to affect her.

"That smell's intoxicating Harry", said Hermione. "I think it might be some sort of pheromone." She went to a nearby bookshelf and too down a book on magic. She put the book on a table and leant over it, one arm of either side of the book. After a short search through the book, she found what she was looking for. "Here it is, the pheromone of Sirius. It's a magical pheromone that turns girls into sex slaves. Apparently any male whose penis begins to emit it will compel any available girl to have sex with him. When he cums into her, the cum will contain enough of the pheromone to transform her into his sex slave for life. It says the boy and girl will not mean to have sex, they just somehow will whether they want to or not. It says they might not even know they are having sex. How is that possible?"

"Oh no, look in the mirror Hermione", answered Harry.

Hermione looked at the nearby mirror on the wall of the common room. In it, she was leaning over the table and reading the book as she had thought. However, she was totally naked, Harry was fucking her from behind. "Oh my God, we ARE having sex! It must be the magic, we didn't even realize we were doing it", exclaimed Hermione.

The moment they saw the image in the mirror, they could see what they were actually doing. They had removed their clothes and started having sex while thinking they were just talking. The spell had muddled their perceptions so they hadn't even known.

Harry tried to remove his penis from Hermione's vagina, "It's no good", he said, "I can't pull it out. My body just won't obey. Hermione, see if you can walk forward, sideways, just get my cock out of you."

Hermione was clearly staring to feel her orgasm approaching, "Nothing's happening when I try to move away. I can't stop fucking you. Oh Harry, you've got to stop yourself from cuming into me. If you do, I'll be turned into your sex slave!"

Hermione's hips thrust back as Harry's thrust forward under the influence of the spell. Harry felt his penis swelling as he prepared to cum into Hermione.

"I think the spell will end when I have my orgasm", Hermione gasped as she began to climax, "Once that's happened, I should be free to walk away. Harry, you've got to hold back. DON'T CUM INTO ME!"

Hermione began to pump her hips back faster and faster. She cried out as she orgasmed, "Harry, don't cum", she said through clenched teeth as her orgasm hit.

Unfortunately Hermione's tight vagina had done an excellent job of stimulating Harry's cock. A torrent of pheromone laden cum poured into Hermione.

"Oh shit!", Hermione exclaimed as she felt Harry's cum pouring into her.

"Sorry Hermione", said Harry as his penis pumped more of the cum into her that would transform her into his sex slave.

Once they had orgasmed, the magic released them. Harry and Hermione, parted and began to put their clothes back on. The clothes were on the floor all around the area they had been standing in. They must have been taking them off even as Hermione was reading from the book.

"Are you all right Hermione?", Harry asked. "You're not a sex slave are you?"

Hermione slapped him, "I most certainly am not your sex slave. Your tone of voice sounded rather like you were hoping I was. The pheromone takes time to transform a girl into a sex slave. If I can use the douche of Isis before the transformation is complete, I'll be OK. I have to get to the potion lab to get some."

Hermione gasped as her breasts suddenly expanded to a cup size larger than they had been. Her hips also became wider. Her whole posture changed, becoming more sexual and seductive.

"Oh no, it's starting", Hermione exclaimed in a sexy tone of voice. "I've got to get to the lab. Whatever you do master, I mean Harry, don't go near any girls. Don't even talk to them. You could be having sex with them without even knowing what you're doing. You'll think you're just talking to them, but you'll be fucking them!"

"I'll stay in my room", Harry replied. "I'll tell Ron what's going on if he comes back. Don't worry Hermione, you'll be OK. I won’t let you become a sex slave.

Hermione put the last of her clothes on (but not her bra as it didn't fit her new breasts) and ran out the door. Unfortunately she didn't realize how badly she stank of the pheromone of Sirius. Every girl she ran past on the way to the potion lab took a deep breath as she smelt the scent that would compel them to have sex with Harry Potter and become his sex slave.