Give her some new knickers (wedgie/bully fetish path)

"So whats with your knickers?" Harry asked, looking right at her crotch.

"W-What do you mean? These are my usual knickers." She blushed under his leer. She was wearing her usual plain cotton panties.

"I mean with your phat arse, you should be wearing something else." He smirked.

"W-What are you talking about harry!? I know i want to be your ass slut, but you cant just look and tell me about my knickers." She yelled. Thank god he put up that charm.

"Hermione, with your arse fetish, you usually wear either really slutty, two sizes two small knickers, or really embarrassing ones. You told me yourself, you want me to wedgie your brains out like that girl did a few years ago." Hermione blinked for a minute, his power taking a moment for her to register before a cute blush settled on her face.

"I- I told you that" she asked.

"Yep, and i heard that you wedgie yourself and refer to your butt in really humiliating ways when no one is around, hoping me or that girl will find you and put you back in your place." He smirked.

"I-I dont do that." She tried to hide. "And for your information, my good panties are dirty right now." She stamoed her foot like a young girl, causing her booty to jiggle.

"Who was that girl anyway, she looked familiar, but you know, slytherins and gryffindors dont get along." He chuckled.