You pull out of the kiss, for the second time. You notice that your dick is getting hard. The mermaid does too. "Um," She says, bowing her head slightly. "I've never actually had..."
"That's OK. You can trust me,-"
You realize that you don't know her name. She notices too and says, "Joan, my name is Joan."
"I'm Mark. Are you sure you want to do this."
"Yes. Please, don't take any longer." She seems anxious to get this started.
You pull her back into the kiss, holding the back of her head. You let your tongue wander to one of her small nipples, sucking on it, and gently pushing her onto her back. You then move onto her other nipple, tracing circles on it with you tongue. Joan is moaning slightly, her eyes closed. Your tongue wanders down her stomach, which is soft, and you finally reach her pussy. Your hardon brushes her tail as you spread her lips just far enough to stick your tongue into her. She moans as you suck and lick her pussy, fucking her with your tongue. She giggles, moans, and then giggles some more. She climaxes, bucking her hips wildly. After a minute she stops.
She props herself up on her elbows. Smiling gently at you. "Can we do more?"