You and your step sister Alyssa had a fight at school because she was making fun of you in front of her cheerleader friends and you blurted out that she was adopted and wasn't really even your sister. It seems that your sister was a late bloomer and until this year she was unpopular and you would tell people at school that the two of you weren't related. You had lots of friends and always teased her mercilessly.Then overnight she grew boobs and was hot and became head cheerleader. It was like the tables had turned and all of a sudden you were the unpopular sibling. Later at home she comes into your bedroom and surprisingly doesn't seem angry anymore."We should talk about about what happened at school," she says. You start to tell her that you're sorry and you shouldn't have done that but she cuts you off, "It's not a bid deal, I knew I was adopted." You're confused but before you have a chance to respond says that there is something YOU don't know. She tells you that she has magical powers and that she is going to make you her sissy slut! You start to think that your sister has really lost it, "yeah ok, whatever sis," you start to say but then you stop because your voice has gotten a full octave higher. You look helplessly at Alyssa as your hands reach down to feel your breasts grow! "Do you like your new boobs?" Alyssa teases. "They're so perky and firm just like mine!" she laughs. "What the fuck are you doing to me?" you ask in your girly new voice. " I already explained it. When I turned eighteen I got magical powers, as my birthright. Now I'm going to get back at you for all of the bad things you have done to me". "Look at how long your hair is getting!" Your waist is shrinking under your hands just as quickly as your hips widen."I know you've always been jealous of my curvy body." Alyssa says with a devious smile. Your legs are smooth and hairless and so long. "Why don't you look down your pants? Your dick is gone! Now you have a tight little pussy instead!" your sister says with a big smile. You gasp in horror as you reach down and come up empty handed. "Isn't this great? I'm going to tell everyone at school that you're my cousin from out of town. The good news is that now you get to wear women's underwear and you don't have to hide it. Oh you didn't think I knew that you 'borrowed' my bras and panties on a weekly basis?" You can't believe your ears. How did she know? You have been trying on her bras and panties for years. Women's panties are just so much more comfortable.And it turned you on to try on your sister's underwear because as much as you didn't want to admit it to yourself, you fantasized about her all the time. "I'm also going to make you suck cock, and not just anyone's cock. I'm going to make you suck my boyfriend's cock" Alyssa laughs again. "I know you hate him, but you're going to love his thick cock. As soon as you feel him in your mouth you're going to BEG him to fuck your virgin pussy! This is going to be so much fun isn't it?" she says with a big grin.