You watch as more of Mandy's legs became covered in scales, while they fused together to become a tail. Half of the scales stop around the waist of her body, while the rest of them grew on her legs, as they fused together becoming one limb. Her pussy was saved, but Mandy's legs almost became one long mermaid tail.
You watch as the final change completes, as Mandy's feet flattened to become tail fins, and the legs finished fusing together, completing her new tail. "It worked," You say, while stunned. "I know," Mandy says, as she began to swim closer to you. "I'm just as surprised. So, wanna have even more fun?" "But what will happen to me if I place my penis in a mermaid's pussy?" You ask, while confused. "Nothing," Mandy answers. "You'll be perfectly fine, and I might even do the same once we head back to dry land."