As Emily rode Mike to their mutal ecstasy, she felt his leg wrap around her tail. It didn't surprise her that he might want to wrap both legs around her tail, but only one seemed odd. Then she realized his leg felt like it was sliding around her tail, almost as if it was growing.
"Oh yessssss, you're sssssssso perfect..." exclaimed Mike.
Emily was amused he was hissing his s's.
"I don't know if I ever want to ssssssstop thisssssss..." replied Emily.
But it couldn't go on forever - at least not the sex. Emily could feel the climax building. Her tail squeezed Mike's tail and it squeezed back at her tail. Wait, what? But that caused them both to lose control and orgasm. Emily collapsed on Mike as the couch felt like it might buckle under their weight.
"That wasssss amazzzzing..." said Mike.
Emily could only smiley and manage an "Mmmmmmhmmmmm..." as she lay exhausted. Her and Mike holding each o ther in their arms, her tail intertwined with his...
...wait, there it was again. Mike's tail. Mike didn't have a tail. Except Emily's senses told her that he did, that her tail felt what was deciededly not a human leg but another snakey tail - a conclusion supported by the way they were intertwined.
"Mike!" exclaimed Emily.
"Yessssss?" he asked. A forked tongue flicked out from behind his teeth.
"You're a naga too! But how?! You didn't put on the other ring yet!"
"No. I don't need a magical ring to become a naga. I couldn't tell you before because I didn't know how you'd react. But once you became a naga - especially just to please me and without knowing I was one - I knew I could show you my real form."
"But how? You never turned into a naga before in the time we've been dating, not even when we've had sex before."
"I can turn into a naga because..."