Amy's oral sex brought you to a series of mindblowing orgasms. After some time to recover, you were ready to return the favor. What neither of you had counted on was how long you had been on the floor. You had splashed some water during your fun in the tub and were of course wet yourselves, but both of you had dried off - mostly - as had the floor.
Before you could get started, Amy shivered and her tail began to split and return to legs. Amy sat up and scowled, disappointed things had ended too soon.
You flopped to one side, watching her transform back from mermaid back to human and realized you would be next. Suddenly you weren't feeling so well. There was a burning sensation in your chest and the feeling that something unnatural was going on between your legs. You shivered as your tail began to split into legs, like Amy's had, but there was definitely something more. You felt dizzy and lay back on the floor, clutching your torso.
"What's wrong?" asked Amy.
All you could do was moan. Suddenly your back arched and your eyes went wide as it felt like something was coming out of your vagina. You were left panting on the floor as strange sensations flooded your brain. You slowly sat up and realized your chest felt lighter. Looking down you saw your penis.
You felt confused. Of course you had a penis, you were a man. Weren't you? Your brain was in a fog.
"Did I turn into a mermaid?" you ask.
Amy blushed. "Uh, yes. My fantasy seems to have worked out a little odd."
"You...you wanted me to be a mermaid?"
"I'm bi" admitted Amy. "I had a fantasy about being a mermaid who turned men she had sex with into lesbian mermaids. I fantasized about what they would be like as mermaids. I never really thought about what happened when they transformed back." She thought about what had happened. "This could be kind of fun actually."
"For you maybe. This is pretty weird for me."