Julie looked at her brother's cock, breathing heavily both in panic and in desire of having that thing inside of her. Julie didn't want to commit incest on her brother, let alone get impregnated by him, but it was mating season and the last thing she wanted was to not want to mate with the closest merman near her.
She slowly flicked her tail and closed her eyes in quiet submission to her brother's fishboy parts. She was merely inches away from having one of Derrick's penises inside her vagina before she suddenly felt herself shoved aside by another mermaid.
“Me first! Me first!” Kimmy yelled.
Miley looked at her sister and chuckled. "So, you want him, too?"
Kimmy nodded. "I always thought he was just adorable as a human but now…" She looked at Derrick's blue tail as she licked her lips. "He's perfect."
Miley grinned. "How about we share? There's enough of him for the two of us."
Kimmy grinned back. "I'd love that, sis." She turned to Derrick, who was now starting to get his senses together. "So, how about it, Derrick? Want to have sex with the two of us?"
Derrick gulped. He wouldn't consider himself a ladies man at all - As he spent far more time talking to female NPCs in 3DS games than talking to girls at his school. Regardless, he knew he couldn't throw away his chance to lose his virginity to the first mermaid he ever saw and talked to, plus if it meant getting a chance to bang her older sister too, it was a bonus.
"Yeah." was all the new merman could say before the two mermaids eagerly lowered themselves onto his two dicks.
"Umm…" Derrick stammered. "I do have to warn you two. This is my first time, so I'm sorry if I make any mistakes or… well… Can't orgasm." He said with a blush.
"Nonsense." Miley replied. "You'll do fine. Just thrust your body and flick your tail."
"Yeah, just do that and let the process do the rest. You'll find the rhythm, I promise." Kimmy said, reassuring her merman with a kiss on the cheek.
With one final gulp and a deep breath, he later nodded. "Alright, let's do this."
Meanwhile, in the distance, Julie just recovered and was grumbling from the surprise shove Kimmy gave her.
In a sense, she was grateful that her mind was no longer in deep heat but she was still a bit pissed that Kimmy didn't warn her before Julie was promptly pushed away.
"Hmph. I wonder how Miley and Kimmy are doing." Julie turned to a sight that made her mouth drop.
Derrick was sandwiched between Kimmy and Miley, and actually doing it with them!
Granted, he could only hump and thrust forward due to his lower body only having one limb now but neither the two mermaids cared. If anything, now that Derrick had only one limb, he soon found his rhythm quickly and his two mermaids responded by thrusting their own hips back to match his rhythm.
Miley and Kimmy hooted and howled in pleasure. Never before had their slits been penetrated by such a long and hard dick penetrating their tight but soft inner walls.
Kimmy especially enjoyed the experience as she kissed Derrick's cheek again and lovingly stroked his shaggy hair. "How are you holding up, handsome?"
Derrick could only let a long moan in response but the young mermaid giggled as she took it as him doing strong.
“Well, I think the path forward is clear,” Kimmy said, smiling softly. “Two beautiful lovers meet, taken by one another, a human man and a mermaid. The mermaid turns the human into a merman and the two make love under the ocean's embrace. Would it not be even more romantic if the mermaid became a handsome wife for him?”
Derrick only let out a grunt, overwhelmed by the feeling that he was in paradise.
The mermaid’s pussy was tight around his large shaft, and the instinctual thrusts of his hips combined with the gentle clenches from Kimmy’s vaginal muscles were sure to make Derrick orgasm in almost no time at all. “Mmm, I’ve never had sex a mermaid before... Let alone marry one. But yeah, it would be quite romantic.” The merman said, with as much nonchalance as he could manage.
Kimmy smiled in joy and she laid her chest on top of Derrick's and finally said the three words she always wanted to say. "I love you."
Kimmy wrapped around Derrick's shoulder and gave one long passionate kiss on his mouth.
The kiss was what finally pushed Derrick over the edge and climax. The merman felt something hot and sticky race up the length of his two cocks and spill out the tips with bursts of pleasure that rocked his whole body and made Derrick moan loud enough that the whole beach would be watching if he still remained on land.
With that, Derrick filled the wombs of Miley and Kimmy with his seed. He leaned back and released his two penises from the mermaid’s tails, basking in the sensations and in the joy he felt when he realized that he just had his first time with two mermaids, of all things!
"Was I...okay?" Derrick asked a bit facetiously.
"Okay? You did great!" Miley cheered.
Derrick grinned at that and was about to say something when his eyes widened at the sight of Julie swimming towards him, probably ready to lecture him on the implications of what he just done.
However, just before Derrick was ready to receive a nagging, his hands were soon grabbed by Kimmy and the two quickly swam away.
"What the… What are they doing? Where's she taking him?" Julie asked, feeling panicked about losing her brother.
"Relax." Miley assured her. "Kimmy couldn't have taken him far. She's not the type to swim away like that. Just follow my lead."
Julie nodded as she and Miley followed the two starfish-crossed lovers.
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And so Kimmy swam and swam, with Derrick taking in the sights of the sea throughout the surprise trip until she suddenly stopped in the middle of a coral reef surrounding a large colorful seabed.
"Hey, umm…. No offense but… Why did you take me here?" Derrick asked.
Kimmy smiled. "Well, you were such a good mate that I wanted to show you something. It’s only the first day of the mating season—and I’m already ready."
“Ready?” Derrick raised an eyebrow. "For what?"
"To spawn!" Kimmy said in glee.
The mermaid spun around so that her belly faced the seabed, her opening pointed at the bowl-shaped little valley in the sand. The face she made as she began to push was the first Derrick ever seen in a girl but a beautiful sight for sore eyes. He even found it cute when her gasping cry of passion gave way to a rather ungirlylike groan, then Derrick saw a cloud of − something − poof into the water. It looked like an emission of some kind of fluid or vapor from her opening, a mix of bright blue and copper in color, and as it cleared away, he saw a pile of little round orbs of the same colors, about the size of shooter-marbles, settling into the depression.
Kimmy continued, and with each contraction, another few orbs spilled out of her vagina and into the sandy nest. Even as it petered out, Kimmy opened her eyes and her gaze locked onto Derrick —a mix of love and satisfaction he never quite seen anywhere else before.
Derrick swam towards Kimmy, looking at the glowing orbs in wonder.
"Kimmy, are those... those pieces of treasure?" He said curiously.
That prompted Kimmy to laugh. "No, silly! Those are eggs."
"Oh…" Derrick said casually. It took him a few seconds before the realization hit him. "Wait, you're telling those are… are...?"
"Our babies!" Kimmy finished in joy.
Derrick was about to say something as he looked down and saw that his two pensies, that he didn't have a moment to let back into their sheath, were letting out a small trail of white liquid, the remains of his first orgasm, onto the eggs.
He gulped and he laid his head down. Their deed was done, and fertilized.
In less than a day, he turned from a regular human boy who spent most of his free time playing video games into a merman who was now an expectant father to a whole freaking school of merchildren - With the amount of eggs reminding him of the beginning of Finding Nemo.
Regardless of how he felt about this, the last thing Derrick wanted was to let his eggs be consumed by a barracuda or any other sea creature that might prey on his future children. He loved them.
Kimmy turned to Derrick and could tell that he was experiencing a tornado of emotions. Smiling, she wrapped her arms around him and gave him one more passionate kiss - Reminding him that he wasn't alone in his journey of parenthood under the sea.