Chad couldn't tell how much time had passed in the dimly lit green marble room. Was it 10 minutes or almost an hour now? It was hard to concentrate anyways; trying to disentangle from their mucky wrapping felt like it was just making things worse. The seaweed felt much tighter now than it did when they were freshly bound. Chad's moaned echoed as William gave him one hell of a hickey.
"I thought we were trying to break free...?" He whimpered.
William nodded absently, his eyes betrayed a lustful haze. "Huh? Oh yeah sure."
He felt William pressed his cheeks against his as more thrashing happened down below. Chad winced as his balls felt so full and compressed constantly being pressed against William's own between their hips.
"A-ah, William stop... I'm gonna..." Chad breathed into William's ears.
This caused William to convulse even more, thrusting his hips into Chad's "I cant...! I can't stop moving!"
Chad couldn't concentrate anymore and arched his back as William kept pushing his body down with his own. His knees and feet were pressed so tightly against William's and he wasn't if he was imagining it but the seaweed felt tighter and harder the further down it went. Was it beginning to dry out? Maybe it would be easier to break it if they kept at it now.
Chad felt William rest his chin on his shoulder. He seemed distracted by something. "My toes feel weird... you don't think?"
"I don't know." Chad whispered through his heavy breathing, he could tell his breath was hot by how sweaty William's neck got. "But I think it's drying up. It's gonna be easier break off now!"
"Right, we better get to it then." William set off like a dog in heat, humping his legs more and more against the layers of seaweed and also Chad's legs. Despite all the grinding that have been slowly exhausting the two boys, Chad felt a weirdly warm sensation tingling at his feet. It was different than just the sweatiness of the hot seaweed sauna, pinchingly numb even.
His toes wriggled weirdly, and he was having a hard time feeling William's own. All he felt was just the stiff, hardening seaweed and that worried him. That pins and needles spread upwards just as his ankles felt like they were goop. Everything felt alien down there and worse still, where was William's legs? or... fins...?
The boys felt the other person's legs slowly vanish inside the weird cocoon and their bodies bent differently than before. The warm feeling crept past their knees which gave the cocoon a more fluid wriggle and William couldn't poke his kneecaps sharply against Chad's or the seaweed walls anymore. The tingle escalated into a burning glow as it scooted up their thighs. It felt really sticky in there, they didn't know where exactly since it every sensation felt awkward as if they were touching each other's skin and themselves.
Chad gasped and William knew exactly why. It had now reach their groins. He felt it deep within his nether regions, a searing sizzle behind his churning balls. The seaweed sack was thrashing like crazy as the boys struggled with the rush of arousal and adrenaline. Without their hands, they could only hump their bodies together to find some relief.
"Will...iam." Chad whimpered and fought to keep his eyes open and stared up to his fellow football teammate.
William was panting heavily and hearing the smaller boy's pleading voice, he nodded and kissed Chad's lips roughly.
As the burning sensation swelled and their bodies flexed and grinded on one another, both boys climaxed in unison. Thick ropes of cum spurted out against their chests and bellies just as the entire seaweed prison cracked open with a loud tear. Chad thought it was almost as if that was intentional.
They both expected to lie back on the marble, exhausted and spent from their unexpected happy-ending-spa-time, but they couldn't. Something was still keeping them tied together.
William propped his arms up and turned white; Chad had to see what happened to them too. Both boys were silent with their mouth hanging open. The attendants were right... but they were so wrong too. They didn't make mermen, they just made a merman.
Where their legs had been there was now a glittering silver fish tail. Not fish tails. Just one. and it was theirs.
Both boys were still human from the crotch up but right below was when their flesh, and their separation, ended and scales began. William snaked his fingers down their crotches and got aroused as his fingers grazed the sensitive spot where their flesh fused. What would be their thighs were now a scaly, tubular mass with their torsos jutting out above like a forked tongue. They still had their human cock and balls though, snugly squished between their bodies like pearls in an oyster.
William tried to flick his new tail, or their new tail rather. He pressed his dick against Chad's and saw that the tail bent backwards to his side of the table smoothly with no indication of his old knee and ankle joints. They realized that the fish tail was perfectly like that of a real fish. They were now looking at the underside of their tail and William and Chad both controlled the right and left side of their swing.
Chad tried to move it now and had to press into William's body to swing the tail and fins to his side. They both looked at the vertical tail fin and back to each other, understanding that if they were to swim then they needed to grind into each other taking turns humping and being humped.
"That's actually kinda hot..." William muttered out loud and Chad grinned.
"Oh yeah? I mean I didn't expect to be a merman today but I don't mind it if I get to be with you." Chad reached his arms around William's neck, smearing their cum.
"Yeah." William shrugged and returned the hug as he let his hands hang low, noting that while it was scaly; he could feel that Chad still had his butt. Whether that was intended or a side effect of not enough seaweed, William didn't care. More for him to grope later anyways. "If I had to get stuck to someone in a fish tail, I guess you're not so bad."
The two boys kissed on the tattered remains of seaweed, unable to go anywhere, and idly flopped their tail fin on the marble table.