Grabbing the vial, you hand it to your twin, who looks at in curiousity and in suspicion. "What's this?" He asks.
"Just a little drink to celebrate me returning to normal." You reply, a crafty smirk on your face. However, your twin doesn't seem to pick this up and he gulps down the vial, before retching in horror. "What did you give me?" He yells. "Oh, Just a little payback" You reply with a grin on your face.
As you watch, you twin suddenly grabs his head. Around his hands, his hair begins to turn a shiny luxurious blonde, which spreads down his hair, which is growing at an extreme rate. He looks up at you, and his eyes suddenly flash, turning a sky blue.
His waist seems to get slimmer, and his ass and hips seem to get quite more luxurious, causing them to rip his jeans and underwear, and revealing a quickly shrinking cock. The man organ seems to shrink and shrink, before being 'eaten' by his new pussy, which was void of hair.
His/her nipples suddenly seem to protrude, and they can be seen clearly, poking through her shirt. Then the chest area on her shirt suddenly seems to tent, and fat begins to build behind them, becoming breasts. They continue to push through the fabric, growing larger and larger. They pass C cups and continue to grow. Finally, the shirt rips, and falls to the ground, revealing a large pair of soft luscious breasts. They still swell, until they stop, huge bouncing orbs capped with perfect dark brown nipples and 3 mm areola.
The new young woman looks around at her surroundings. Thankfully, you had included a touch of 'memory wipe' formula in the mixture. "Where am I?" asks the girl, as she looks around, her gentle gaze moving from item to item around the room. She then sets her eyes on you, and you see something in her mind suddenly change, as she begins to massage her breasts. "Oooooohhhhhhhh" She moans, and you realize that her breasts must be immensely sensitive, allowing immense arousal and sometimes, orgasm.