Not much, at first.

For the first two weeks Hermione would've been forgiven for thinking that the rule book hadn't had any effect at all. Very little seemed to change, at least on the surface. If someone looked a little bit deeper some signs of what was going on became plain as day. No change was detectable with any of the girls but there were signs of something else going on with the boys. Younger boys were much more prone to huddling together and very obviously kept their distance from any of the older girls. The fourth years had it worse off since most of the girls in that year were hitting their growth spurts before the boys were.

The older boys, at least in Gryffindor, tended to be acting a lot more confident by contrast. Especially the ones who were a fair bit taller than all their female peers. From time to time Hermione caught sight of them putting the moves on one girl or another, and it seemed they were having some good success at it. Certainly Ron and Harry had been acting a fair bit more charming and playful around her. Neville still looked rather nervous from time to time. But he seemed to be the only one really having a hard time. Once Hermione caught Harry and Ginny hiding in a corner away from the main hall practically trying to inhale each other's faces. Hermione could almost see Ginny's toes curling in her shoes as Harry held and gently caressed her face.

Hermione should've expected it. She couldn't imagine any Gryffindor was a secret supremacist which meant they were all perfect lovers. And they could no longer masturbate amongst themselves if they wanted to avoid shrinking. They all needed to get at least one girl to go steady with them and they had the skills to manage it. Good for them. Hermione was glad that so far her rules weren't having any unfortunate consequences for any of her friends.

The Hufflepuffs appeared to be in the same boat. The younger boys kept to themselves, the older boys were acting a little more outgoing and confident. In Ravenclaw though there were a few boys who were looking a little more nervous these days. They were more isolated, more prone to keeping to themselves. The few times she had seen them approach a girl they got swiftly shut down. Oh dear, they were in trouble. Hermione had no sympathy for them. All they had to do was give up just one belief and they would be perfectly safe. If their pride was more important than their futures, that was their choice.

The Slytherins were where the real changes were most obvious. Oh they tried to play it cool at first. They paraded about, sneering and looking down their noses at everyone. But the cracks were starting to form. Their eyes were a little bit more wild, they huddled together a little more closely, they were a bit more **** when talking to the Slytherin girls who were growing less and less interested in them. And yes, they were growing a bit shorter to.

Three weeks after Hermione had changed the rules Draco tried to provoke Harry into a fight in the halls between classes. He sported the usual drivel, his family this, his father that. Hermione had just walked up to him, held her hand flat out, put it to her forehead and then moved it straight and level forward, until it passed over the top of Draco's head. The bigot who had once stood over her was now a few inches shorter. She smiled at him, he broke out in a cold sweat. She licked her lips, he stumbled backwards to the ground.

"That's a good look for you Draco." She said towering over him. "All the way down there people might not notice how short you're getting. Maybe you need to start practicing some self discipline."

That night she had sex with Ron for the first time. He had treated her to a private dinner up in the astronomy tower, surrounded by warming charms. They had watched the stars rise above them as they talked about the future, their hopes and plans for after graduation. She snuck him back to the girls’ dorms to one of the private rooms that were reserved for situations just like this. He ate her out until she was screaming his name then fucked her until she was seeing stars. She rewarded him by growing his cock until it was nine inches long and he thanked her with another three orgasms.

"Thanks." He half murmured as they slowly fell asleep in each other's arms. "I needed that. This whole no masturbating without shrinking thing has kind of been taking a toll on me, I have to admit."

"Anytime you don't cum inside me is a complete waste." Hermione said back. "That dick was made for me."

"It's yours whenever you want it." Ron vowed. "I don't know how I've lived this long without your pussy either. Just say the word and I'll drop whatever I'm doing to worship you instead."

Hermione took him up on that offer. Over the next three weeks she had him bend her over school desks, pin her to library shelves or try and break whatever bed she was lying on. She had thought it might get boring after a while but it never did. He was a kind and generous lover. He always made sure she came at least once before unloading into her and his record so far was making her cum five times in a row before he finally released himself. She was loving every minute of it. She grew him a foot taller as thanks, burned away all his body fat and left him a towering Adonis of muscles and glory.

Ron wasn't the only one to get a glow up either. Ginny had exactly zero shame and knew precisely what she wanted. Harry was now pushing almost eight feet in height, looked like he had been carved from granite, and had a bulge between his legs that nearly made Hermione jealous. Every time he walked by, Ginny got a look of almost stupid bliss on her face and would nearly throw herself at him.

There were obviously a few other guys in the other houses who had found very satisfied partners. But it appeared that most girls were keeping their guys on short leashes. Some guys would lose an inch or two in height then the next day they were back to normal and looking very grateful to one girl or another. Other guys were getting glow ups in the opposite direction. They were getting pretty, more feminine and graceful. Maybe even a little more slender. Never short enough to cross the danger zone but held in just the right spot to make them perhaps a little ****. Hannah Abbot was practically leading Neville around on a leash these days. Hermione wouldn't be surprised to see him showing up to class in make up or a girl's dress in a few days.

Six weeks after she had changed the rules it looked like the Slytherins were about to break. Not a boy in the whole house still stood more than five and a half feet tall. Most had slipped down to the high fours. The girls of all the other houses started watching them like hawks. No one made a move yet. But it was only a matter of time before one of them wound on the menu.

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