The passionate kissing continues and you become incredibly hard. You caress her breasts as she removes your shorts and waste no further time to be inside her. Your lovers embrace sinks to the bottom of the pool. Her tail spasms with each thrust. You climax together in an unbelieveable moment. The two of you drift back to the surface exhausted.
Topaz moans. "For a mermaid to go a year without sex is such torture. I had so missed that."
You smile an exhausted smile. "So when do I start to transf..." Your words are cut short as unfamiliar sensations wrack your body. Your legs feel stuck together. You feel your feet flatten into a tailfin. You look down to see your legs become one solid tail and small fins similiar to those that Topaz has also develop. Your tail becomes scaled like hers but a darker shade of blue and more muscular. You can feel your manhood still intact, but withdrawn inside your tail. You feel refreshed.
Just then you hear the door to the pool open and look up to see Caroline walk out. You're sure she can see you in the pool but suspect its dark enough she can't make out that you now have a tail.
You consider what to do...