(A/N): This is my first attempt at merlock, so be gentle. I don't pretend to be an expert on nautical terminology. Feel free to correct me. :D Comments welcome!

...

John Watson had loved fishing since the ripe age of seven, when his uncle had dragged him away from a bi-yearly family gathering and convinced him to go sea fishing in a rickety, peeling boat. John had taken to it quickly, learning to cast the line with precision impressive in one so young. Fishing became a significant pastime during his adolescent years, continuing all the way until he boarded an airplane destined for the cartilage spattered sands of Afghanistan, and the hobby came to an end.

Only when he returned to London with a ruined shoulder and a limp did John consider getting rekindling his interest. Ella strongly encouraged the idea, stressing the importance of any activity that would provide John with a sense of peace. He couldn't argue with her, and thus began taking a train out of London every other Sunday morning and into Brighton. Sometimes he helped himself to a quick sandwich from a shop before going out on the water, and sometimes he preferred the gnawing of his stomach. Wearing a blue tartan button down and sturdy boots, John would pick his way down to the pier, locate his boat—a marrow-coloured humble affair, load his fresh tackle into the compartments beneath the salt encrusted bench, and make sure to check the fuel supply before teasing the engine to life and backing out into open waters.

He always arrived before dawn, so he could admire the lingering clusters of stars overhead; little colonies of caged fireflies. The silence was incredible, the break from human activity overwhelming. Nothing to fill the ears but the pull of the tide and the soft lick of water against the hull of the skipjack.

John was sitting with his pole in hand on morning just like this, sucking his bottom lip between his teeth and chewing it, pensive. Had it not been so intensely still, he surely wouldn't have noticed the gentle splash to his left. As destiny would have it, he did, and looked around for the noise, pulse accelerating.

"Hello?" he called out, training his eyes on the watery expanse.

Another splash in reply, louder than the last.

John frowned and tugged experimentally at his line. It gave easily, making it clear that no creature was toying with the other end. He told himself he was being ridiculous; seals inhabited these waters and that was most likely the source of movement. No reason to worry.

He was just refocusing his attention on the task at hand, calm again, when there came the most furious splash of all, large enough to throw water in his eyes. Blinking, he twisted around and looked down. Perhaps it was seawater clouding his pupils and his empty stomach, but his gaze landed on what looked like a human male, bobbing in the water studying John with opalescent grey eyes.

"Christ," John gasped, adrenaline prickling behind his ears. "What are you d—"

The man dropped beneath the surface, leaving a flurry of bubbles behind. Dumbstruck, John hung over the edge of the boat, waiting for the strange apparition to return. Humans could not last with no oxygen in their lungs. But minutes passed and passed, and John remained alone.

Shaken, he reeled in his line, shifted gears, and sped back to the harbour.

...

Apparently an empty stomach had nothing to do with it, because John saw the same man bobbing next to the skipjack two weeks later, and he could still taste the cherry preserves from breakfast.

"Fucking shit," he said very eloquently upon the stranger's arrival. "Who the hell are you?"

The man regarded him in total silence and, wide-eyed, John took in the mess of dark curls (adorned—accidentally or on purpose John could not infer—with a thumbnail sized lady-slipper shell and bit of bottle green seaweed), the pale but sun burnt skin, the angry scratches on shoulders, jaw, and ribs, and the film of sea salt coating the cupid's bow.

Same as last time, the stranger slipped beneath the waves without a word and John sped the hell back to civilization, except this time he could not stop thinking of mermaids.

...

The third time happened a bit differently.

For two hours John had been sat in stinging June sunshine without the faintest sign of movement on the end of his fishing line when there was a mighty yank and his heart leaped into his throat. All satisfaction died quickly, however, when he discovered he couldn't reel the damn thing in. He struggled and wrestled and pulled, and then, to his great astonishment, the dark haired man burst to the surface with the metal hook caught between his callused fingers. And he laughed.

And he laughed.

And he laughed.

John stared at him with a mixture of horror and fury, and said, very quietly, in the precise tone which he used to bring terrorist factions to their knees, "Put it down."

He did.

They looked at each other, squinting in the harsh light reflecting off the water.

"Who are you?" John asked for the second time. "Are you—" He cleared his through, mouth tasting of nickel. "Are you a m—"

The man dove out of sight, dousing John thoroughly, but even in his anger he saw, virulent and lustrous, a powerful tail arcing and dipping beneath the sea.

"Well, buggery fuck," he breathed, and threw the skipjack into action, speeding toward the bay with a thundering heart.

...

John did not return to Brighton for over four months. First there was an episode with Harry and rehab, then there was a holiday in St. Andrews, then his hours at the clinic became extraneously and inexplicably busy, then his bathtub decided to act like a goddamned fountain and he was compelled to spend five days replacing the corroded pipes, but beneath all of that, there was still the memory of the man with the tail, and this beyond all else was what kept John from his seafaring excursions.

When at last he did return to the harbour, it was not under happy circumstances. His girlfriend had just broken up with him, and, although he remained polite in her presence, the minute the door clicked shut behind her John threw his jacket on and marched to the nearest pub, where he ordered two whiskies and a port to wash it all down. After which he caught the last train out of London and arrived in Brighton well after dark. He stumbled down to the pier, found his boat, flung off the tarp, clambered aboard, and reversed full-throttle into the darkened bay, heedless of the electric tang in the air that warned an incoming storm.

Only when he was three miles from shore did it begin to rain, so torrential that John would have had to yell to be heard over the din even to someone sitting directly beside him. And only then did he realise he was completely out of petrol. Sobered by fear and the gravity of the situation, he gripped the sides of the boat, wishing he had his orange inflatable life vest. The waves were growing in size and intensity, and knocked him about, making his organs lurch and his pulse spike. He began to chant a stream of curse-riddled prayers and everything was awash in roaring sound and his very existence seemed to narrow to a hazy black blur as the skipjack flipped and he was thrown into chaos.

...

There were no witnesses to the following sequence of events: a pale body coursing through the deep, the unconscious fisherman encircled in strong arms, two heads breaking the surface while lightning crackled everywhere—

...

Consciousness came to John as a steely jolt and he opened his eyes, staring into the blazing white hole of the sun. His limbs felt achy and sore, and his skin stung with numerous cuts. But, to his great surprise, he was not a corpse at the bottom of the ocean. Miraculous. He stretched and rolled carefully onto his side.

"Hello."

"Shit," said John, finding himself face to face with a set of familiar grey eyes. "Shit."

"You seem to have a particular affinity for that word." His companion stretched as well, a sinuous arch of muscle shifting over rib cage and spine.

"You're a mermaid." John coughed, and unpleasant mix of bile and saltwater on his tongue.

"Wrong. Mermaids are female. I am a merman." Said merman looked unspeakably pleased with himself and John could not fathom why.

John glanced around at the pebbly ground beneath them. The merman flicked his tail.

"I'm alive because of you," John remarked, because he knew, just as he knew the bullet was going to miss his mate and come directly for him that day.

"Correct."

John pushed himself into a sitting position. "Why?"

"I may frighten humans for sport on a daily basis, but, unlike my brother, I rarely allow them to drown."

"What a comfort," John murmured. He swallowed hard. "Where the hell are we?"

"I believe you call it Sussex."

"Jesus, well, I have to— I have to get back." He risked a look to his right. "D'you, er, have a name?"

"Of course." The merman's eyes glinted savagely. "We are not animals."

"I didn't mean—"

"It's Sherlock."

"Sherlock," John echoed.

"Yes. And I'm assuming you have a name, too?"

John flushed. "John Watson."

"How human," Sherlock remarked, but he was not laughing. He looked away, rubbing a stone between his palms.

John stood. "I'm off, then," he said awkwardly, and Sherlock's zygomatic arch seemed especially pink just then. John's stomach performed a weak pirouette. "Goodbye. And thank you. really."

Sherlock met his eyes finally, as silent as the day the first encountered each other, eyebrows raised as if to say what of it?

"Um," said John. Then he turned and walked barefoot toward town.

...

There were certain things John would not tell his therapist. I still have nightmares. I can't stop thinking about war. I kept my Sig. It's in a drawer in my desk. I might use it sometime.

I am in love with a merman.

Perhaps in love was an exaggeration, but what else could the infatuation, the attraction, the vertiginous sensation that made his head spin and beckoned him to fall, be named?

He studied her beige rug and didn't say any of this.

...

Curiously, John did not see Sherlock the next time he went fishing. It was a Tuesday and he'd been unable to wait for another glimpse of the object of his fixation. But no dark head appeared above the blue, no strange eyes regarded him with solemn scrutiny; no one toyed with his line. John caught a moderately large bass, but in the end he dropped it gently back into the sea, because his heart wasn't in it that day.

He returned twice more, once on Sunday, then on Wednesday, but to no avail. It was as though Sherlock had vanished for good.

...

John was taking a walk along a craggy outcropping of rock and sand several weeks later. It was nearly Halloween, but London had reached record temperatures; children were racing about in little more than their pants and vests, everyone's cheeks were perpetually flushed, and dogs could only pant listlessly in the shade. A wind off the sea ruffled John's hair back from his sticky forehead and he was intensely glad he had escaped the city while he could.

A trio of teenagers cycled past on bicycles circa 1960, and John lifted his hand in a wave. He was beginning to perspire in his aubergine button down, so he slipped it off and continued in his tee-shirt. The mess of underbrush and shrubbery to his right clear momentarily and he was granted a spectacular view of the ocean. He admired the wind-whipped peaks of waves crashing against the cliff, until he realised he wasn't alone. There draped lazily over a particularly large boulder, was Sherlock. Arms cushioned beneath his skull, he lay with his face tilted skyward, touched with the rosy stain of sunshine.

John found it suddenly difficult to breathe.

His body shuddered into action without his brain's consent and moved him away from the path, nearer to Sherlock's supine form. It was a relief when he reached the sand and no longer had to tiptoe. He perched on the far edge of the boulder when within touching distance, and held his breath, heart skittering madly.

"Sherlock," he managed, finally.

Sherlock opened his eyes and turned toward John, look like a pink and sleepy nymph. "John," he breathed, voice rough with sleep. "I didn't expect to see you."

"You've been avoiding me," John remarked.

"I have not."

"I've been out three times in the last week and you never turned up. Do have some sort of policy about never speaking to people you've saved again?"

Sherlock propped himself on his elbows. "We can't—" He broke off, looking vexed. "We can't just be friends, or something. I'm not human, John. I wouldn't expect you to look for me. That's not what people do."

"I'm not people," John said immediately.

Sherlock smiled. "I know."

"Then stop acting strange. This could be bloody weird, yes, but not impossible."

"You're saying you want to…?"

"Dunno. We could keep each other company sometimes."

"You want me to accompany you on fishing trips."

"Maybe."

Sherlock twitched his tail and it brushed briefly against John's bare ankles. He started, tingles working their way down his spine.

"This isn't advisable, John."

"Neither is popping out of the water next to people's boats and scaring the living shit out of them. Somehow I don't think rules will much impede you."

Sherlock flicked sand in John's direction. "Perhaps we can devise an arrangement."

...

They'd been out fishing together exactly six times—Sherlock's forearms draped over the edge of the skipjack, gazing up at John as he told stories of gunshots and genocide—when John was confronted, well, accosted would be the better word, by the only other merman he'd ever seen.

"John Watson," said the merman, gracefully ejecting a spout of sea water from his mouth.

John stared, flummoxed. Where was Sherlock? "That's my name, yes," he said rather testily. "What do you need?"

"Let me put this simply: you have no business fraternizing with our race, nor do you have the right to initiate contact with one of our kind."

"We're talking about Sherlock, right? Because he initiated contact with me."

The merman gave John an unctuous look. "Be that as it may, from now on you will not seek him out."

"Why not? You can't dictate what I'm allow—"

"I am the ruler of this colony, John, and I have every right to dictate. Is that quite clear?" The merman's thinning ginger hair slipped into his eyes and he pushed it back, somehow still imposing as hell.

"You're all mental," said John, and clutched the accelerator. "This is mad."

"I need your word, Dr Watson."

John glared at him, jaw set. "Fine, yes, you have it." Then he sped off, thinking of the route to the nearest pub. "Crazy bastard," he muttered, and blazed into the bay.

...

Nightfall found John sitting on a lonely stretch of beach in somber starlight, waiting for the buzz of alcohol to fade. He was remembering the earlier confrontation, thinking bitterly of never seeing Sherlock again. He lay back and gazed disparagingly up at the heavens. He was fucked. And he knew it, too. In so many ways. After inestimable minutes, he heard his own name in a voice deep and achingly familiar.

"John."

He looked left. Sherlock was curled on his side in the sand in the shape of a bass clef, watching him with tired eyes.

"How long've you been here?"

"Only a minute. Something's wrong," he observed, a petulant furrow between his brows.

"No," said John. "Nothing's wrong." He wet his lips and wondered whether he should leave.

Then Sherlock seemed to have some kind of epiphany, because he inhaled sharply and said, "You have no obligation to listen to anything Mycroft says. He's got a bit of what you would call a Napoleon complex."

"Sorry?"

"Mycroft. He stopped you earlier, did he not?"

"Christ, was that who—"

"My brother," said Sherlock, "is an overprotective prick."

"I thought— I thought— Oh," said John, a surge of relief flooding his chest. "I thought I'd never be able to see you again."

"Rubbish," Sherlock declared. "He likes sticking his nose into everything. Ignore him." He swallowed. And then, without breaking eye contact: "Come into the water with me."

"Wha—now?"

"Yes, obviously."

John hazarded a glance at wristwatch. It was well past one o'clock in the morning; highly unlikely anyone would catch them. "Fine."

Sherlock turned his head as John began to undress, slipping into the shallows to wait. When John was clad in nothing but his pants, he shrugged and slipped out of those, too, leaving them atop the neatly folded pile of clothing. Then he scuttled toward the sea, hissing at the first bite of water over his toes, and dove.

He resurfaced seconds later, drenched and laughing. Sherlock was right in front of him, tail flicking lazily in the depths. They were not touching, but close enough that even the slightest movement would have them pressed together. John looked into Sherlock's irises, still amused, and saw that Sherlock was not laughing at all, but leaning toward him with the oddest expression. And all of sudden they were kissing.

John brought his palm up to cup Sherlock's cheekbone, dazed, and wrapped his other arm around Sherlock's waist. Sherlock tasted of salt and brine and rain, like kissing the very ocean itself, and John brushed his tongue over the lovely crest of Sherlock's lips and into his pliant mouth, so their tongues could stir together.

And they did; sweetly, dangerously, wonderfully. Sherlock pulled John even closer, kissed him even deeper, cupped his face with sand-roughened palms and breathed things into his mouth: John, beautiful, need you, move with me, move with me.

The water was a welcome contrast to the heat of John's arousal, lapping at his naked limbs and hardening cock. He shifted against Sherlock and brought their hips together with a groan, sucking at Sherlock's lips, his neck, his jaw, his eyelids, his cheekbones. They could not stop kissing, and this was fine by John.

He ran his hand down the length of Sherlock's vertebrae, resting his palm against the place where human torso turned to glistening scales, and Sherlock gasped and shuddered toward him as though it were an erogenous zone of sorts, bringing their lips together, and again, and stubble and sea salt and warmth, and again, and then he snaked his arm between them and took John into his hand and fuck.

And fuck.

Long, sure strokes down his length made John's breath come in sharp pants. He clutched Sherlock, as though if he let go he would drown. A quick twist near the glands and there was a tightening near the base of his cock and in his lower back; John arched and dug his fingernails into Sherlock's flesh until they both cried out; Sherlock's hand moving and moving and moving up and down and up down and rocking into him and against him and pressing and breathing and clinging to each other like sea-tossed sailors in a different kind of storm as the tide broke over them and again and again and again and—

...

"Love makes us such fools," Sherlock remarked, months later.

"Indeed," John agreed, trailing his fingers over his companion's scapulae.

Sherlock plucked a rock from the shallows and examined its sharpness. Satisfied, he pressed it to the plain hull of the skipjack.

"What are you doing?"

Sherlock pressed his free hand to his lips. "Wait." After long moments of carving, he moved back and beckoned John over. "Look."

John hung over the edge and read, upside down: Sherlock. Etched forever into his boat.

He met Sherlock's eyes and his throat tightened.

"So you cannot forget," Sherlock murmured, touching John's cheek with damp fingers.

"Wasn't planning on it," John said gruffly.

"Just in case."

John knelt in the bottom of the skipjack with his head next to Sherlock's and their hands entwined, and together, they watched as the sun strained upwards and darkness faded to insignificance.