Kevin grew hard watching the two mermaids making out on his floor. He loudly cleared his throat and they stopped to look at him.
"Would you ladies like me to take you somewhere more comfortable?" he asked.
"You wouldn't happen to have a hot tub, would you?" asked Gisela.
"I've got one out back by the pool." Kevin had in uncovered and turned on for just such an opportunity.
Gisela and Lilia smiled at each other.
Kevin picked up Gisela and carried her out to the hot tub. Setting her down on the edge, the two kissed.
"I'm glad you didn't break up with her after all" Gisela said. "This should be fun."
After another kiss, she slipped into the hot tub. "Don't keep me waiting too long" she said with a seductive smile.
Kevin returned to Lilia who had shed her dress.
"So how did you meet another mermaid?" she asked.
"It's a long story, but the short version is I didn't know she was a mermaid at first and I thought our relationship wasn't going anywhere" Kevin said. "I'm glad I was wrong."
"I like her. At least you have good taste."
Kevin picked up Lilia and they kissed.
"Before we go, get one of my serum vials out of my purse."
"What do you need for now?" asked Kevin.
"It's not for me; it's for you. The serum temporarily turns mers into humans, but it also temporarily turns humans into mers. Then we can really have some fun."
"Great idea!" said Kevin.
He took Lilia to her purse, retrieved the serum, and carried her out to the hot tub. At the hot tub, they exchanged another kiss and Lilia slid into the water.
"Bottoms up!" she said then resumed making out with Gisela.
Kevin opened the vial and found that the serum smelled like fish. He downed the whole thing then stripped off his clothes and climbed into to join the two mermaids. Although he could feel changes beginning as soon as he drank the vial, the water caused them to accelerate.