Beverly insisted she was okay to drive, but on the ride back to your apartment you began to have your doubts. You insist she come inside rather than drive home.
You helped her inside and she laid down on your couch. She asked for water and you returned with a plastic cup, which she slowly drank.
"What do you see in the mirror?" you asked.
Beverly didn't respond, though her cheeks seemed to redden. She finished her glass of water and asked for another. You went to the kitchen and refilled the glass from the faucet. When you turned around, you were startled to find Beverly standing there, topless. You immediately began to feel aroused. She grabbed you in a hug and kissed you deeply. The cup of water spilled over both of you as it tumbled to the floor. You could feel the splash of water trigger something inside you. As the two of you made out against the counter, you didn't notice Beverly reaching behind you to grab the sprayer. You heard the faucet flip on a moment before water sprayed you in the back.
You broke away from Beverly's grasp, and wheeled around and she continued to spray you. Looking down you could see orange splotches appearing on your legs. Your shirt began to feel tight. Then Beverly turned the sprayer on herself. You lunged for the sink and turned the water off.
"Why did you do that?" you asked.
"Because I want to fuck your mermaid brains out" said Beverly.
Did her breasts seem smaller? Her hair shorter? Her shoulders broader? Were those teal splotches on her legs?
"What did you see in the mirror?" You were pretty sure you knew the answer.
"A handsome merman, with a teal fish tail" Beverly finally admitted. "As much fun with our girl-on-girl this afternoon, if you'd turned into that merman..." She shuddered at the pleasurable thought. "But you turned into a mermaid, so... Let's just say I love cock. I loved your human cock in me, but now that it seems I can't have that anymore the idea of being about to put my mer-cock in your mer-cunt was just too good enticing."
You stumbled backwards out of the kitchen. You were going to turn into a mermaid for the third time, and your girlfriend was about to turn into a merman for the first time. What happened this afternoon was one thing, but what Beverly wanted to happen now...
Your legs were growing weak. You tripped over the corner of your coffee table and fell onto the couch. You couldn't stand the pressure on your shirt and pulled it off your growing breasts. You heard a ripping sound as your legs slowly became a mermaid fish tail, your shorts and underwear be damned.
Beverly stood and watched you slowly transform into a mermaid. She had clearly dumped more water on herself after you left the kitchen. You could tell her legs were weakening too. Her hand touched your tailfin, rubbed it. The feeling was better than any foot massage could be. Beverly's face was no longer her own: she had the face of the merman from the mirror. Her remaining clothes came off, revealing her teal legs. She climbed onto you on the couch as those muscular legs began to form a fish teal. Beverly pressed her lips to yours and cupped one of your DD breasts. You felt something strange that you'd never felt before...
Soon Beverly's fish tail was complete and it rubbed against yours. The feeling was electric. The two of you continued to make out on the couch, Beverly on top. You felt something poke your vagina. You reached and felt it: Beverly's merman penis. It seemed bigger than yours had ever been as a human. You felt it in your hand...and guided it into your vagina. You...wanted this?!
Beverly gently thrust into you and you gasp. Her fingers yesterday had been one thing, but this was quite another. You were fully a mermaid now and Beverly was fully a merman. Your desires were different than they had been as a human. You couldn't believe the words that you whispered into Beverly's ear: "Fuck me, Beverly, fuck me hard. Come inside me." She obliged.