Helen pulls you out and then lifts you up to her face. Dangling upside in front of your giant sister. Helen leans forward and you can't help squealing with terror as she slowly licks your body, from head to toe.
"Mmmm, my pussy tastes good", she says softly. "I may have to eat you again once I'm done fucking your body". She giggles as she stands up and swings the chair around so that the backrest is facing her. She places you down on the seat and you feel a tingling in your feet. You look down and watch helplessly as they melt into the fabric.
"There", Helen says. "Now I can sit on you".
With that, she straddles the chair, and you. She then slowly starts to sit down. She pauses briefly when the enormous, glistening lips of her inner labia are directly above you. Despite the terror you're feeling. You can't help looking up in fascination as the lips get increasingly larger as they drop slowly toward you. The lips eventually touch your, then they part and Helen's pussy swallows up your head and shoulders. Slowly, Helen lowers herself down, feeding you to her vagina as she does so. Like before, the muscles of her pussy contract tightly around you. She's so wet, and the walls of her vagina so velvety smooth, that despite the vice like grip of her muscles, your body slides inside your giant sister easily, the walls stretching to accommodate you. Within a couple of minutes, you've been swallowed whole by your older sister's gargantuan vagina. Helen then begins to slide up and down. Slowly at first, but at regular intervals Helen increases the speed and force with which she rides you. You just can't believe this is happening. Your own sister is currently having sex with your entire body. The whole thing is completely surreal. What feels like gallons of Helen's lubricating fluids flow down your throat, like a sickly sweet wine. But despite this, you can still breath perfectly normally. You can see too. But the only thing to look at is the fleshy pink wall pressing on the front of your body.

By now Helen is sliding up and down your shrunken body as fast and as hard as she can. You can hear muffled moaning and groaning. Inside, it's getting increasing hotter and wetter. Suddenly, you hear Helen let out a long loud scream. At the same time, Helen's vaginal muscles contract even more tightly around you as she slams herself down, grinding the outside of her pussy on the chair. You find yourself trapped inside her as Helen has a very powerful orgasm, her pussy filling up with what seems like a lakeful of her fluids. It seems to go on forever, but more likely only a minute or so. Then, it slowly dies away. Helen keeps you inside her for a long time, then she lifts up and lets you out, sitting down again directly in front of you. You look to find Helen looking down at you with a satisfied grin on her face, and covered in sweat.
"Shame you had to be born a boy", Helen says softly. "You'd've made a fantastic cock".
You resist the urge to insult her.
"That's a taste of what you're life will be like from now on. As far as I'm concerned..you're nothing more than a living dildo. I'm gonna use you every day. But don't worry. In a few years, you'll have forgotten what it was like to be a normal boy. You'll just yourself as my toy. You'll think your only purpose is to give me pleasure. And you'll love it so much, you'll beg me to use you. Until then, I'll enjoy making you suffer...slave".
Helen laughs. At the same moment, your feet reappear and shrink back down to one inch.
"I'm gonna take a shower now", Helen says. "I'm gonna put you somewhere safe. You may as well consider how you're gonna cope with being your own sister's slave".
With that, Helen: