Becky was beginning to act more and more passive, especially around you. Whenever she would lash out at someone for no reason, you would knock her off her pedestal with clever insults and an obnoxious attitude. She was use to getting away with anything, and her bad temper did not help any.
If she did get in trouble, all she would need to do is throw some of her parents money at people, or seduce her way out of these troubles. Even though she began to hate you, she was offering to buy you lunch, and even began to buy you stuff in an attempt to make you leave her alone. You were smart, and knew what she was doing, and refused all her charity. When that happened, Becky resorted to seduction, which didn't work either. Becky's personality had made it easy to ignore her beauty.
But Becky's temper built up a rage within her. She wanted to lash out, and insult you in her stupid way, but knew that you would make her feel much worse. So she would continue trying, and then, a breaking point.
One day, you noticed something odd about Becky. She seemed taller. Not only that, her boobs looked bigger. You had never been attracted to this girl since the first time you had seen her, but her new size got you going.
Luckily for you, Becky had given up on seduction, and begun to fall into an extremely passive phase. You weren't even trying, but Becky's weak mentality made her so afraid of you, that she would do anything for you. She was like a beaten puppy.
"Hi...hi Moe." She said.
You nod at her, and waved very slightly. Pushing Becky over the edge, and giving her a very small mental break down.
Each day became the same. Becky would act normal to her friends, but then, she would walk into class, and the very sight of you triggered her passiveness.
Not only that, on a daily basis you noticed Becky's change in size. Each day, she seemed to be a few inches taller. Only after a week, she had gone from 5'8" to Moe's height, and her chest ballooned out to a F cup.
People asked her if she was ok, and she nodded, not saying anything. But she wasn't. Not getting her way with you was, oddly enough, a traumatic experience to her. You were triggering subconscious reactions, which, in some odd way, was making her grow.