A/N: For some reason, I wrote a mermaid (merman?) AU for my future spouse because I love them and therefore must write 20 different stories for them. I like making them happy. It's the single most fulfilling thing I can ever do.
I'm gonna throw a bone and say this takes place in 18th century Portsmouth, New Hampshire.
In the middle of the night, on a beach that was only scarcely graced with the light of the moon, it wasn't uncommon to hear strange things coming from the ocean. It also wasn't uncommon for a guard to slack off and wander away from his post, most commonly to wander over to a nearby pub. What made both things uncommon was when they intertwined. What made it even more uncommon was when it wasn't a common guardsman, but the captain himself.
The first few times captain Dok took the night shift for himself under the premise that there was "unruly behavior" reported through several eyewitness accounts, no one said a thing. Keep quiet, the public must not know, the captain is fully capable of handling an issue that most likely resulted from the restless whalers that recently returned home after a four year voyage. Except after the first several days, it became suspicious, and on the fifth day when he didn't return from his post at midnight for the next guardsman to take over, it became alarming.
The very first thing that Erwin was able to confidently confirm with both himself and any outside parties was that he did not believe in myths.
They're myths. Stories used to scare small children. That's all there was to them.
So naturally, as a skeptic, when he reached the docks that night with Hange yipping away at his heels, he didn't think twice of the mist that lingered over the sand. The ocean yawned, smoothing delicately over the soft, glittering surface of the wet sand, then pulled away with an equally delicate gasp. Being so close to the ocean, he could feel the chill of its foamy breaths sink through the layers of hemp that typically shielded him from the cold when he patrolled the town's streets.
At the very first chill that raked down his spine, Hange abruptly stopped in the middle of their sentence with a heavy sigh, a puffy cotton-like cloud rushing out between their lips. "I'll check the alleyways!" Hange stated, finality evident in their tone. Then, less sternly, they whispered, "How much you wanna bet that he's drunk?"
Erwin pursed his lips, not pleased with having to come nearer to the ocean, but not quite upset enough to protest. At Hange's large, impossibly bright smile, he offered, "Ten shillings."
It was small, almost insignificant, but it was enough to satisfy them. Hange left him at the beginnings of the beach, where sand mingled with dirt and stone, their conjoined lamplight dwindling and leaving Erwin in a small flickering bubble that illuminated just a few feet ahead of him. Their footsteps slowly suffocated and died, leaving him alone with the abyss that reached out towards him, climbing up the beach far enough to throw salt in his nose before it receded with a loud, spiteful hiss.
The ominous beauty of the ocean fascinated him; there were things people never thought twice about, not until they were given the chance to appreciate it in another light. Or lack of one - the clouds overhead slowly inched towards the moon, and the glow of white and silver against the ocean vanished. Erwin held the lamp out further ahead of him, until he came close to the pillars of wood that marked the mouth of the nearest pier. The pier was empty, or at least appeared to be empty, and with the limited view, there wasn't much he could do.
By the time he had reached the end of the pier and returned to the mouth of it, the clouds had steadily unveiled the moon, allowing her to shine brightly upon the beach again. With this, his field of vision grew, and accordingly, a glint in the corner of his eye caught his attention. At the foot of one pillar, a bolo tie lay at the very edge of the wood, the strings flowing off the edge as if reaching out below. It glowed a deep red, bold and brash and blatant; it screamed of Nile.
Erwin stepped near the edge of sand where bright orange sandstone started, the jagged, uneven rocks leading down into a pit below the pier. He crouched down, stepping carefully over the slippery rocks, and he progressed halfway down the hill before he slipped. He didn't fall, but he did drop his lantern, the sharp, metallic ringing of it echoing loudly in his ears as it bounced down against the rocks and finally hushed as it slid along the sand below and rolled into the water. He followed after it as he regained his balance, more careful on the last few feet of his descent, and picked up his lantern. The lamplight was gone, but he didn't need any extra light besides the moonlight to glance below the pier.
Half hidden by the shadow of the pier, but still illuminated by the moon, a pair of narrowed silver eyes stared directly at him. Erwin wasn't quite sure whether he dropped his lantern again or not, his mind hyper focused on those irresistibly bright eyes. All thought gradually vanished, washing away with the ocean as it reached up to lap at his ankles, then crawled back into the abyss with a gentle murmur.
One slender hand slowly reached up to the sharp, beautifully unmarred face that belonged to those tantalizing eyes and wiped at the thin lips that curled ever so slightly into a coquettish smile. It pulled away with a smear of scarlet across the skin. Erwin regained some sense of control, his chest fluttering, the fleeting weight in it painfully apparent as if he had forgotten how to breathe for a few seconds. The smile on the man faded, sharp eyes never once blinking, never moving, poised on him with an ominously inscrutable expression.
The man before him straightened, slowly, deliberately, revealing the body that he had been crouched over moments prior, similar to a predator caging in its prey. The whispers of the ocean crept out of the corners of Erwin's mind and allowed him to process that, beneath the thin, pallid man lay a body, nearly unrecognizable now. It was littered with teeth marks, the jagged edges of ripped skin and the ruined fabric of an unmistakable uniform sticking together until it nearly become one.
With a deep, honeyed voice, the man hummed softly, "Yes, sir?"
He was upright now, both arms holding him up, his shoulders cradling his head in an innocent manner. Crimson covered his forearms and smeared against his abdomen, a stark contrast to the ethereal white of his smooth, unmarred skin. Were it not for that, Erwin would have followed the unmistakable pull forward, a calling that made him yearn for more. Instead, he squared his shoulders, now conscious of the heavy rise and fall of his chest, and the man's considerable lack of one.
Trailing even lower, framing the perfect dip of his hips to his groin, a horizon of light green emerged on his skin in a gradient, merging to an exquisite teal as it trailed lower and then, finally, deepening to a strong blue, as bold and bright as the ocean. The fin, thin and curved at the base into an elegant cupid's bow in a thick line of ocean blue, lay just a few feet away from Erwin's left, flicking in the water. The man didn't dare move, and justly, neither did he, not even as the ocean returned again to envelop his ankles in its agonizingly cold embrace.
The man's croon resonated in Erwin's chest, a sound more fascinating than any song he had ever heard before; "Come here."
It was hard not to take a step forward. His body screamed for such, chest ached for it, mind swarm in desperate circles in an urgency to respond to the voice that called for him. There was nothing demure about his demeanor any longer; he narrowed his eyes, a pointed tongue darting out to lick his thin lips, and damn it all, Erwin followed it with a shallow sigh. It was enough to encourage the man to try again.
"What's wrong?" Petulantly, the man pouted, reaching forward again, slowly lowering himself into a predatory crouch as he pleaded with a silvery voice, "Come here. I'm so lonely."
It almost felt wrong, to stand there against the tide, to refuse to let himself fall into the easy flow of it. Maybe he would have, if those mesmerizing eyes hadn't left his, if the glower of molten silver had stayed on him any longer than it had.
"Erwin?"
Hange's voice was heard a considerable distance away, but it was no doubt getting closer, following the hastened thudding of boots along the sand. Erwin realized, now, that he had begun to step forward, had already been on his heel to give the man what he wanted. The chill sunk through his coat and into his skin, wracking shivers down his spine, and backing away was now an achievable feat.
Erwin watched the carefully constructed insouciance fall from the creature's face as he called back, "I'm here."
Hange finally reached him, calling down from above, "What happened? Did you find something down there?"
That small, pallid face, still so tantalizingly ethereal, still so smooth in a way that begged for one's touch, contorted into a grimace. He was angry, no doubt, and some part of the charm that had swayed him and kept him locked in place for so long elicited a brief pull of guilt in his chest. The man before him, crouched low over the mutilated corpse, readied to strike, tail receding, lip pulling back with the furious furrow of his brow, the beginnings of pointed teeth starting to emerge -
"Nothing." The man stilled, face falling, eyes widening as if genuinely surprised by the response. Erwin repeated firmly, fully by his own accord, "Nothing. I dropped my lamp."
He heard the crunch of boots against the rocks, pebbles falling from above. "Well, hurry up and grab it. It's cold down here."
Erwin knew, with a painful regret, that he needed to go. The ocean retreated back into itself, leaving a glittering sheen on the man's lustrous tail. His scales glowed a baby blue, similar to the ones that had gathered around his forearms, now clean and pure after the water had enveloped them many times, more often than Erwin had realized. There was nothing more beautiful than the way his tail, with tips whiter than any shining pearl, reached up to curl around him, curving protectively around a slender shoulder. It was diminutive, defensive, but not enough to be considered submissive. Erwin assumed that this was the man's way of giving him permission to leave.
He found Hange waiting impatiently for him, rubbing their hands together furiously in a futile effort to stay warm. Hange shakily murmured something about never returning so late at night, when the world seemed to freeze over, but Erwin didn't complain. He didn't need to.
There was nothing that could keep him from coming back.