"You won't be using it to have sex with me or Jasmine right now, though," Cathy smiles. Edward nods along, and you start to realize they both know something you don't. "See, Morgan here drank the strawberry water, and I think he's almost ready for you."
She carefully sits you down on the bed, and reaches behind you to pull off your swimsuit, neatly tugging it off you and leaving you naked. Edward pulls off his swim shorts, and your eyes widen as you see his erection. You've never felt the way you do seeing his penis before. He leans in and cups your cheeks, and as you kiss you feel like your body could melt into his. Cathy gets behind you, and you whimper against his lips as her hands touch your chest.
"Good boy, Morgan," she breathes into your ear. "Or should I say, good girl."
You look down and your heart races as you see how large and puffy your nipples have gotten from her touch. While you breathe heavily, your chest seems to swell up, and as it grows it feels more and more sensitive, especially with her fingers rubbing and pinching at your nipples.
A shiver runs through your body as Edward's hard cock touches yours, and as it slides downwards and presses against your scrotum you feel... pliable. Like if he keeps this up your body will just capitulate to him. He kisses you again and Cathy's lips press at your forehead. "Let him make you female, Morgan," she whispers. "Trust me, it feels so, so good."
While your body was going to do so anyway, her assurance makes it happen even faster. You feel yourself be castrated against his masculine touch. Your testicles tug up inside you to reform into ovaries and your scrotum recedes inwards and peels open into labial lips. As his cock slides inside it seems to carve a vaginal passage into you. He holds still for a few seconds and then pulls back and starts to fuck you, and every time he thrusts into you it sends a stronger shockwave of pleasure through your body. You feel your penis rapidly shrink away, and hear Cathy whisper "Good girl" at you as you become emasculated. Soon only you have only a tiny sensitive clitoris and a pair of vaginal lips Edward is eagerly thrusting in and out of. His balls slap against you with some of his thrusts, and it feels like an exhilarating reminder of how much you've transformed.
At last you moan out in your high-pitched female voice and wrap your legs around Edward's back as you clench around his shaft. After a few more thrusts, he groans and you feel his warm seed soil you inside, seeping into your freshly-developed womb.
You feel like you're gonna pass out, and the last thing you hear is Cathy whispering, "You did so good, Morgan," while she kisses your head.