A Potion for a Mind Controlled Sex-Fiend Step-Sis

My step-sister is smoking hot. I don't know what it is about her, but she really turns me on. It might be something about her fiery red hair and bitchy attitude, but whatever it is, I really wanna fuck the hell out of her. But I know she'd never go for that. I probably couldn't even pay her to touch me. So, when Step-Mom and Step-Dad were out, I decided to fulfill my fantasy even when I knew she wouldn't want it. I bought a special potion at the store that, when ingested, turns whoever you want into your little whore. I walked into my step-sister's room with the potion in a cup, and she immediately bitched for me to get out. I knew she was waiting for her boyfriend, so I convinced her to hang out with me for a little bit until he got there. I handed her the cup and she took a sip, "Ew, what is that?...Did you give me tap water? You know I hate tap water." That sip is all I needed to get things started. While I waited for things to get...interesting, I asked her to play a game with me. She rolled her eyes, "If I play one game, will you go away?" It wouldn't take long for the potion to work, so I dealt her some cards, and we played a card game. As the game progressed, she started complaining about a headache. Her vision got blurry, and she was having a hard time seeing her cards, as well as playing the game. She fanned herself off, "I'm getting really hot." The next thing I know, my step-sister is jerking my cards down from my face, and she's in nothing but lingerie. The potion changed her appearance! She looked at me with seductive eyes, "I don't know what's wrong with me, but I'm feeling so fucking horny." She continued to fan herself, and then groped her chest uncontrollably. Her hand went down to her pussy, "My pussy's, like, throbbing." She quickly unfastened her bra, "It's like I just can't keep my clothes on," and pulled off her panties, masturbating insanely. She went crazy. My step-sister couldn't control herself in front of me.