"Emily, for as far back as you remember, you've always been deeply aroused by... The idea of turning boys into girls. "
Emily's face goes deep crimson and she looks away, the Veil obviously having worked its magic. "H-how did you know?" she said, blushing.
"I always knew." you said with a smirk. "And here I thought you were such a prissy and proper little prude... When it turns out that you always were a kinky little thing?" you ask, knowing your sister was now incapable of lying to you.
She shook her head. "It's not what you think! I just... Look, do you know how awkward it is to be a girl?" she scoffs. "Of course you don't. You never had to think about what it's like to be smaller, to be weaker, to know that more than half the world could overpower and ravished you if they wanted to?"
"Uh... No. I admit I don't." you shrug.
She nods. "Exactly. You have all this power, all this safety and you get to never think about it. You take it for granted. So when it comes to... those fantasies... God, I just can't help myself! I'm not even sure if I'm attracted by boys or by girls yet but... When it comes to the idea of a boy, of a man having everything that makes him big and strong taken from him? To see him be... reduced to a girl, like me? To feel humiliated and weak, to feel vulnerable and cockless, to know that he's now just as short, feeble and desirable to men as girls are? That.... That just.... "
Her sentence trails off, as your realize her hand is moving softly between her thighs, bunching up her skirt and making her breathing more erratic and punctuated by airy little moans.
You would like to reply something witty... But your cock straining painfully against your jeans robs you of all wit. You can only watch your nubile little sister rub herself shamefully before you, thinking about turning boys into girls.
"Y-you were my first fantasy of this sort you know?" She mewls, not stopping her finger in the slightest. "I hated how big and tall you got after your growth spurt... I hated how easy it was for you to pee when we went on hikes with dad, while I had to wait for a bathroom. I hated every girlfriend you had, knowing your penis gave you the ability and power to dominate them... I wanted to take it all from you! So many nights I dreamed about how I'd humiliate you of I could turn you into a girl..." she moans softly, rocking her hips naughtily against her hand at the thought.
A stray thought passes through your mind, making your erection stiffen all the more with how exciting it felt to you... As you listen to her explanations, you couldn't help but think how arousing it would be to give her that power over you... To let her humiliate and emasculate you...
You shake your head. That was a stupid thought! YOU were in control of HER. You had no intention of relinquishing this control just so that you could be turned into a tiny, cockless little thing to be teased and humiliated by your sister... Did you?