Your doubts about your prowess with these mermaids are answered as you pleasure the second, then a third, then a fourth! Each time, after a mind blowing orgasm, you find the next enchantress is able to arouse you yet again.
From time to time you glance at Vanessa as she takes the mermen in succession. Her "legs" (if that's what they are anymore) are much longer, streching nearly five feet from her hips. They move about in the water with complete fluidity, no longer restricted by bony structures. Their color has changed too. Like you saw in her feet, a blue green tone extends all the way to her hips. Her skin below her waist is beginning to section itself into a covering of scales.
You know that similar changes are happening to your own body and relish each new sensation. You revel in the freedom of movement in you own lengthened "legs" as they bend in any direction you choose. Your fifth mermaid stokes you ass as you pump you longer cock into her. As she rubs, you feel the resistance of the scales that have emereged on your body. As you cum, you "hear" Vanessa scream in her own orgasm.
As you partner withdraws, you are in a haze if exhaustion and euphoria. Still floating underwater, you feel hands, again, caress your member.
Then, a familiar voice enters your head, sweet as ever, but, somehow, even more enticing.
"Oh, this is so nice now," Vanessa says to you! "I can't wait to put it inside me."
You look down at once, sure enough, your girlfriend has taken a position at your cock, urging it forth. but Vanessa has changed. Her legs are no more! In their place, a long, sleek mermaid's tail undulates in the water. Her eyes are now the deepest blue, her chest quite full and enticing. Vanessa's longer hair floats about her head and flows through the water.
"You like fucking mermaids don't you?" Vanessa asks.
You nod in agreement.
"Well, why don't you fuck me then? I'm a mermaid now, you know."
She kisses your hard dick before swimming up your body and impaling her tail on it. You pump harder into your transformed girlfriend.
"That's it," she screams and moans in pleasure, "FUCK ME! Fuck my mermaid pussy."
As your hips pump back and forth, your legs are drawn together. You feel them merge into a single, long tail of your own. Taking the end of your tail, you entwine yourself around Vanessa, pulling her onto you.
An orgasam hits you again. This time, you cum flows for minutes instead of mere seconds. Vanessa takes all you can offer. As she separates from your body, a few drops of semen float through the water. Vanessa smiles at you before opening her mouth and lapping the remnants up with her tounge.
You take a moment to see what you've become. You're a merman in every way. Your long green tail propells you through the water. You circle in a flip and return to your mermaid girlfriend. Vanessa smiles as you bury your cock into her yet again.