This work is cross posted on Ao3.

Thanks to the lovely ladyscribe for beta reading.

Landing in the ocean from twenty meters up was a little more than slightly painful. Steve wasn't relieved, however, that he had survived the drop, because looking around the empty horizon, things were going to get much worse.

Just moments ago, he had been fighting in New York against the latest bad guy and assorted evil henchmen, when one of the black-clad mercenaries got a good shot at him with a blue light gun. It was all too much like the Hydra weapons, and he had braced himself for, well, whatever happened to the men he had lost. He was sure it wasn't pleasant. Instead, he found himself in deep, freeze-your-ass-off, blue-grey water as far as the eye could see- no land in sight. It was so cold, Steve shook himself, wiggling his arms and legs, in an attempt to remind his body that it wasn't under the ice again.

What he would give for a dove with a twig, because the salt water was stinging like a Portuguese Man-of-War in the deep wounds decorating his legs. He looked down to check that there weren't any jellyfish or other creatures with stingers.

Much to his shock, there was something down there. It was a vague shape, and Steve couldn't tell much other than it had a long tail, and was very big. Possibly as big as him, even. He didn't like his chances with a deep sea creature on its home turf. Steve was still trying to convince his body that he was going to be okay, never mind his brain, which was trying not to think about the odds of being found before he drowned, or a creature like the one circling below pounced.

The ocean was a very big place, and Steve really was not liking the odds.

The creatures' circles were getting closer.

He held onto his shield, which, thank god, was floating, bracing himself for whatever came up. Just let it be quick.

Something flicked at his boot-clad foot , and he jerked his leg, making it twinge with pain. It was a shark. It had to be. The thing was huge and- oh god, the cuts in his leg. He was bleeding all over the place, and what kind of creatures exactly live in this area of the ocean? He had no damn clue, because he had no fucking idea where he was. He eyed the creature in the water worriedly. For the second time in his life, he realised that, short of a miracle, there was no chance. He wasn't going to get out of this one alive.

Something grabbed his foot. And tugged. He managed to grab one last breath before he was completely submerged, shutting his eyes tightly against the salt water as the creature held on with an iron clad grip. He let go of his shield in an attempt to swim for the surface, thrashing furiously trying to get rid of the creature. To his surprise, it released him, and he swam his way up to the surface, gulping in air, and blinking the salt water out of his eyes.

A shape was forming through his blurry vision, floating in front of him, and as he blinked, the shape cleared.

Relief that it wasn't a shark, or giant octopus, or a very big fish with a big set of snappers was suspended in disbelief, because there was no way it could be that.

It wasn't possible.

On second thought, Steve had seen much weirder stuff than mermaids, so he really shouldn't be freaking out at the idea of a half-fish half-human creature. It –she?-was beautiful. Waist length hair clung to her face, the ends still floating in the water around her, buffeted gently by the small currents, twisting into tangles and knots before sliding undone and twisting away. The way her red little lips were open in wonder, her deep brown eyes wide, made him think he was probably just as much a novelty to her as she was to him. But it was the tail he was stuck on. It was a warm coral red, shimmering under the surface, gently flicking to keep her afloat.

In shock, he sunk, until he was completely submerged. Despite being underwater, coughs racked his body, trying to expel water only to have it flood back in. Then a hand seized his own, tugging him up, until he was coughing and spluttering at the surface. Having finally got his breath back, he stared at her. She was positively beaming at him.

"Um... Thanks for helping me," Steve said politely.

The smile faded off her face, and she cocked her head to the side.

"Can you understand me?" Steve asked. She gave an over-exaggerated shrug, and shook her head slowly, looking at him beseechingly. It made sense, really, that a creature that seemed to regard him with as much amazement as he gave her, would be unable to speak English. Fortunately, body language seemed to be a fairly global thing.

She opened her mouth to talk. Unearthly sounds came flowing from her lips, like the sea and waves themselves were singing, full of life and laughter.

Steve repeated her shrug and shake of head back, shivers shaking his shoulders more than he intended, and for a second, his legs, which had been giving long slow kicks to keep him afloat, gave out, and he sunk suddenly again, this time with no notion of how deep he was.

The girl grasped him under his arms and propelled him to the surface, her tail whipping against Steve's leg . This time, she did not relinquish him from her tight grip as she frowned at him. Steve relaxed into her, no longer having to rely on his own body to keep him upright.

She manoeuvred one hand until it was right in front of his lips, gently feeling the flow of his breathing. She grinned at him again, as if she'd figured out some incredible puzzle.

"Yes," Steve said, understanding. He pointed to the sky, taking a deep, exaggerated breath.

"Air," he explained. He pointed to the water, shook his head, and coughed, "water."

She nodded, signaling that she understood. At least, that's what he hoped.

The shakes and shivers were getting worse, and the girl hugged Steve close, putting her hand up to cup his cheek, stroking his chin, big eyes worriedly examining him.

He looked into her warm brown eyes, only a few inches from his face. They were filled with compassion and intelligence, and, perhaps he was only imagining, an odd glint of cheekiness.

She mimed taking a deep breath. Steve wondered idly if she was amphibious, but grinned back at her, despite the cold, and copied her. A second later, he found himself wishing he hadn't, as she dragged him deep under water. He tugged desperately at her hand, wrapped tightly around his wrist as she swam strongly down, down, down.

Maybe she was so happy to find he couldn't breathe water because she knew she could kill him. Wasn't that how the old sailor's tales went? A siren from the deep, happy to drown any man it saw.

She was a fast swimmer, obviously, and he soon found himself wondering what was going to kill him first- the lack of oxygen, or the water pressure. He was sure they were already deeper than a normal human could swim unaided.

But the scared feeling, along with the cold and the pain from the cuts in his legs was leaving. He felt lighter, somehow, buzzing. It almost reminded him of before the serum, that time he and Bucky had gotten drunk together. That was odd. Thinking of Bucky didn't hurt so much down here. He felt light and bubbly, happily intoxicated, sharing a moment with his best friend.

He let out a laugh, clasping one hand over his mouth as bubbles poured out. That was bad wasn't it? He needed that. They were important, he was sure.

He watched the bubbles float up, up, up to the top. They were so very pretty. And then they were gone. The little mermaid was pulling him, and he watched everything slowly blur into blackness as she tugged him down further.

Something else was coming up in front of them, but it was too blurry to tell what it was. Steve was close to blacking out, and then someone was squeezing him tight, and he was gasping for air. Slowly, everything came back into focus.

The first thing he noticed was that he was sitting in sand, his cuts stinging with the little grains in them. The second was that he was in a cave on a little island in the middle, the rest being filled with crystal blue water, and the mermaid was watching him anxiously. The last thing he noticed, as it is something lifelong air-breathers often take for granted, was that there was oxygen.

Still panting, he rested back on his elbows, and stared at the girl. The water painted the walls and mermaid with a waving blue light, like the beautiful art in an animation- too perfect for the grittiness of the real world.

"We are in a cave, probably hundreds of feet below the surface, and there is an air pocket?" Steve stared around, taking everything in."I'm pretty sure that's supposed to be impossible," he gave a desperate laugh, turning to face her.

"And then here I am talking about the impossible as someone who has fought against aliens trying to take over the planet, to a mermaid."

Said mermaid was looking distinctly frustrated.

"One who doesn't understand a word that I'm saying," he laughed again, and flopped onto his back, closing his eyes.

For goodness sake, how crazy was this new world? Mermaids, of all things... Though, in retrospect, they had probably existed back in his time too, unless there was some kind radioactive waste spill in the area- which, for once, was probably the less likely reason.

There was the sound of something heavy dragging across sand, and he felt a puff of air on his cheeks. Steve opened his eyes to look into those of the mermaid.

She had heaved her body out of the water and onto the little island, her tail between his legs, arms on either side of his head, holding herself above him.

One thing that had not been obvious to him, as she had been covered by the sea water and a swirling mass of hair, was that she was very, very, naked.

He turned his head as fast as he could, but not before noticing she had the fullest, softest breasts he'd ever seen.

He knew he was blushing horribly, and he squeezed his eyes shut as he tried to figure out exactly what to do, trying not to be distracted by the very distracting... distraction.

He felt her lower herself onto his chest, and he knew that without the suit, he would feel her- nope, he wasn't going there.

A hand gently stroked his flushed cheek, and two hands grasped his head to turn it to face her. He resolutely squeezed his eyes tighter.

She giggled, and her laughter was just as melodic as the words she had sung. She carefully tugged on his eyelash, gently forcing his eyelid open. Faced with a creature, who may not be human, but was most definitely a woman, and who seemed to have no problem with nudity, it was rather hard to know what to do. Or where to look. But maybe they didn't wear clothes down here, he thought.

Looking at the way she stared at him, curiously, but not lustfully at all, he ignored how his cheeks were still burning, and drew himself up onto his elbows again. She didn't move from her position on his chest, snuggling closer, a warm weight on his cold body.

Steve grinned at her wryly, "You aren't going to get off me, are you?"

She grinned back, then bopped him on the nose with a delicate webbed finger, mock frowning at him.

"You don't understand," Steve nodded, and he felt his heart twinge, both irritated and dismayed that they couldn't communicate.

She pointed to herself, and spoke. The sounds weren't decipherable as words, and Steve was doubtful he'd ever be able to pronounce it, but it sounded like something along the lines of, "d-Ahaa-Rrr-hhh-ie."

Steve tried to say it back, "Daary? Is that your name? It's beautiful."

He got another bop on his nose for his trouble.

He shrugged again, shaking his head, "I'm never going to be able to say it," he tried to explain gently.

She gave him an exasperated look.

"All right, I get it, you don't know what I'm saying," Steve grumbled. He did his best to point at himself, awkwardly, as she showed no intention of getting off his chest.

"Steve," he said slowly.

"Ssss- thieve." Her shoulder shook, and Steve grasped her shoulders in worry, before realising... She was giggling.

"What are you laughing at?" he asked, amused.

"Ssss-thieve," she said again, giggling. He grinned back.

"It's close enough," he assured her.

She rolled off him onto her side, sitting up, and leaning over to peer at his wounded leg. She gave him a reassuring smile, before diving off into the water.

Steve sat up, staring down at the ripples she left on the surface. Once they had calmed, he found himself staring at his reflection in the mirror-like water. His brows had creased, and his eyes looked tired. Without the girl to distract him, all his worries were flooding up to the surface. Natasha had been in the middle of fighting three of the soldiers, all equipped with the same guns that had shot him. While he had complete faith in Natasha, every now and then, someone gets a lucky shot. And the others... Well, there was no guarantee he would see them again.

Then a thought entered his mind. If Hydra's weapons did the same thing, what had happened to all the people who had been hit? Dropped in the middle of a desert? Left to die alone in the middle of the ocean, slowly getting tired, giving in to the waves?

There was a splash, and Daary appeared again. She was grinning triumphantly, carrying with her a bundle of seaweed.

She sat next to his leg, gently lifting his foot up onto her tail. She grabbed the seaweed, wrapping it carefully around his cuts that were already partially healed. It was cool and soothing, and Steve felt his muscles relax as she smiled, tying it off.

Ping.

The girl startled, falling back into the crystal water. Steve scrambled desperately at his belt, as she surfaced so that just her eyes were out of the water.

He held the device, which was blinking red at her.

"See? Harmless," he knew she couldn't understand his words, so he spoke as gently as he could, trying to calm her through his tone.

It was the locator Stark had given him, in case something happened. When Tony had told him it was pretty hardy, Steve hadn't realised exactly how hardy he had meant. It was certainly tougher than that old radio receiver Howard had given him when he jumped out of the plane. It also meant they were tracking him down, ready to take him back home.

He held out the device to her, and she snatched it out of his hand with enthusiasm, shaking it wildly. Steve supposed if it held up under water hundreds of meters down, a little shaking wasn't going to hurt it. She held it up to her ear and listened, though the device had stopped pinging.

She then held it out in front of her face, frowning at the little flashing light.

"Piinnn," she whispered to it softly. Then she shook it again.

Steve shook his head, "It's not going to ping again," he tried not to laugh. Her eyebrows and nose were scrunched up in frustration, and she looked quite adorable.

She scowled, and threw it down into the sand with a harrumph.

Steve burst out laughing. She retaliated by poking him in the ribs.

Cheeks still wide with laughter, his eyes connected with hers. She looked so happy, laughing there with a complete stranger of a different species, who couldn't even pronounce her name. Maybe she was just as lonely as he was.

"I have to go home," he said softy, still staring into her warm brown eyes.

She stopped smiling at his change of tone and cocked her head, raising her eyebrow.

He pointed up. She stared at his hand, and started to shake her head vigorously. She pointed at the sand, at herself. It was obvious. She wanted him to stay here, with her, in her otherworldly home. Steve suddenly found himself wanting to, more than anything. But he had an obligation. To his team. To the people he had to save.

Sometimes he hated himself.

He just watched her sadly, as she tried to persuade him to stay, shaking his head softly.

She scowled at him, before hauling herself onto the sand, and scooting closer until she was almost in his lap. She grabbed both of his ears in a very undignified manner, and used them to tug him forward to meet his lips with her own soft pink ones.

When his team collected him at the surface, no one suspected he had done anything other than float for several hours. He later realised on the helicopter that he had left his shield down in the dark depths of the ocean. But halfway through the flight home, one of the crew handed him his shield. They said they had picked it up, same time they hauled him out of the water. If he smiled sadly when he saw it, the crew just assumed he was reminiscing of times long gone.

No one knew of the cheeky mermaid who had rescued him, and later, his shield.

She was a secret he took with him to the grave.

And if they ever met again, no one was ever going to tell the tale.