"I'm so sorry! I should've been more careful!" I said.
"No worries. I like this, actually. As a matter of fact, I was wondering if you wanted to join me?"
I paused. Was she really asking if I wanted to turn into a mermaid as well? But as I thought about it, I realized that if I really cared about her, I would do whatever she wanted. I swallowed hard, and stammered.
"Only if you really want me to. I wish you could have any wish you wanted."
"Then I wish you were like me!" She said.
I toppled into the pool, my clothes bursting off and dissolving as big G-cup breasts grew from my chest. My shoulders shrank and my ass and pelvis grew, and my waist caved in to become an hourglass-like 30 inches. My legs shrank into my body and disappeared, and my cock vanished as a vagina appeared in its place. A fish-like tail grew from my spine, and connected itself to the edge of my pelvis. I swam to the surface of the pool and gasped, my hair turning pink and growing out to the edge of my ass. I sighed. Was this really what she wanted? I mean, now we can't do it like we used to be able to...
That thought disappeared as she swam up to me and pushed her fish-like vagina into my face. It felt so good that I forgot all about screwing her with my dick. I wished silently that we would remain like this forever, that we could change this world to suit our needs, and that we could change other people to be like us just by having sex with them. Suddenly, we weren't in a pool, but in a lagoon, and there was a young woman sitting at the edge. A young man was sitting beside her, and we couldn't wait to introduce them to our new world.