Author's Note: Based on a prompt: "Sea of darkness" (but also based on a conversation with yumi-michiyo, of course). The underwater breathing thing is taken from the film Hook, an oldie and goodie. Alternate Universe (sort of); this ended up being way longer than I anticipated.

Temptation

She finds herself at the water's edge.

It's the only place where she can find peace, or at least the promise of it, and the waves lap at her bare feet, gentler than usual today. She can't remember when she first started coming here, and has lost count of the number of times she's returned to this spot.

On every occasion, the water is comfortingly cold.

There's something about the way the tide rolls in and out that reminds her of the impermanence of everything, including herself. She's forcefully reminded of how little her own powers, or curse, matter.

(It couldn't save them, after all.)

Her expression turns impassive at that fleeting thought, and she is glad she is here, and not in the castle. There, the thought would turn and churn in her mind, tormenting her until she could hardly bear to face another person (like her sister) for fear that she would hurt them.

But here, it is rebuffed, and then silenced.

In this space, it is replaced with a soft, gauzy sound - almost sweet, she sometimes thinks - one that washes over her like the waves she watches from onshore, and even seems to reach into her body and engulf what remains of her heart. Whenever she leaves it, it feels close to what she guesses heartbreak must be like; in its absence, she craves it in the way that she imagines a drunkard lusts after the bottle.

And when the pain of separation becomes too great, she always finds a way to return, and to feel whole again.

As time passes, she wonders if the sound is changing.

Where before it had no shape to it - only the outline of warmth - she swears that it has slowly turned into something vaguely familiar.

(Like a song.)

It's not one that she knows, or anything that she can remember hearing in passing (not that she's been outside of the castle much, though she can hear the music float up from the town square to her room from time to time). The notes in it are strange and foreign, striking unusual chords, and sometimes even discomfiting ones.

But it is also beautiful, and it draws her in.

At first, she only takes a few steps into the water before realizing that the trail of her gown is drenched, and the air suddenly smells too strongly of salt. In those moments, she quickly retreats, unnerved by her trance... though not enough to keep her from coming back.

Then, when the song takes on a clearer form, almost carrying a sort of tune, she goes further in: waist-deep, sometimes, before she regains control of herself, patches of ice sputtering out from her gloved, soaking fingers. These instances disturb her more than she'd like to admit, and she walks back to the beach with a shiver running up and down her spine.

The sound, however, disappears as soon as she leaves, and she cannot find the slightest trace of it as she tries to find some explanation behind it all - the song, the trances, the craving - and she is maddened by the gap in her memories, raking over her mind again and again until she's nearly made herself sick from the effort.

She tries to avoid the obvious answer for a time, because it scares (and excites) her. She is afraid to return, to see, to feel... but most of all, to lose what little control she has left over her senses, and over her ability to harm.

But a part of her knows that she never had that control in the first place, and knows—

(There is nothing left but to go back.)

A feeling of intense calm rushes through her when she touches feet to sand, unparalleled to anything she has felt in a long, long time.

The swiftness of that gratification, however, also makes her shudder.

The sky is gray and pitiless, hardly an inspiring sight; and yet, as she draws closer to the water, the color transforms into a mosaic of pinkish, dappled hues, like the beginnings of a sunset (though it is hardly noontime).

She hesitates just before the edge, and for a moment the cloudy sky reappears, breaking the illusion.

And then she hears it.

The sound is soft and faraway at first, but it's enough to lower her defenses. Her gloves slip off as if they were never there, and then she's dipping one toe in, then another, and then her whole foot, followed shortly by the other. Some part of her is vaguely aware that she is moving closer, and deeper, but she ignores it.

The sound, after all, is now a song - her song - and it is the most wonderful thing she's ever heard.

"Why are you crying, little girl?"

Her eyes flutter open, though she can't remember ever closing them—nor can she remember crying.

She blinks. "I wasn't," she replies. Frowning, she adds: "And I'm not a 'little girl.' I just turned nineteen, in fact."

She knows she's spoken those words, because her lips move, and the statement is accompanied by a faint memory from her recent birthday - persistent knocking on the door, followed by the sound of muffled weeping behind it - but her voice feels caught.

(As if it were suspended in thin air.)

In fact, her entire body feels that way - floating, like it does in her dreams - and moving any part of it is slow and difficult. Her vision, likewise, is murky, tinted blue-green, as if she is squinting with her nose right up to the spinning globe in her father's study.

"You were, and you are," the phantom voice counters, and it is oddly familiar in spite of her dulled senses. "But I couldn't tell if it was from sadness, or from joy. Do you know?"

Her gaze tightens a little, trying to center on the source of that sound; she wants to summon some annoyance at its teasing tone, but instead only feels a deep, warm contentment run through her veins, sparking along her skin and reaching to her fingertips.

(It feels like magic, but not like mine.)

"I don't know," she says, still unable to see it. She tries to swallow, but inhales nothing. "Who are you?"

An amused trickle of laughter answers her. "I was someone once, like you," the voice responds, its form becoming lower and smoother as it draws closer to her. "But now I'm no one." It pauses, and her heartbeat quickens a little as she feels a presence behind her. "And who are you?"

It's clear to her now, speaking just against her ear, that it is a man's voice... or that it at least gives the appearance of such. The thought would cause her face to flush under normal circumstances, or perhaps ice to crawl out from beneath her in discomfort.

Here, however (wherever "here" is), she is merely curious—or, she supposes, enchanted. "Princess Elsa of Arendelle," she replies. "I will be Queen someday, too."

"Oh, royalty. I used to know a few of those," it (he) remarks, "though you don't seem like them."

She blushes, and then catches a fleeting glimpse of it (him) as he briefly passes in front of her, a swirl of red and blue and green. The sight reminds her of the color of the sky as she touched the water, and her eyes widen.

"You're the one who's been singing to me—"

Her speech is cut off, and though she wants to gasp, she can't. Its (no, his) mouth is covering hers, softly pushing her lips apart, breathing into her; the sensation pleasantly burns her throat all the way down to her stomach, and settles there.

When they part, she can see him clearly.

"You... you're a..."

"Siren, is what I think your kind calls us," he finishes, smirking. His eyes are bright green, sparkling like seaglass, and they regard her lips for a moment. "Did you like my song, princess?"

Her gaze flickers down to see a seaweed-colored, fish-like tail below his bare torso, and somehow the sight is a comforting one.

(I'm not the only one.)

She presses a finger to her bottom lip, and reddens. "Yes—" she begins to say, and then pauses, irritated. She doesn't realize that she can hear her own voice again. "Why did you kiss me?"

His red hair gently waves back as he laughs, drawing her in closer. Her shock keeps her from struggling (much). "I'd forgotten that your kind call it that," he replies, though his knowing look says otherwise. "How odd."

She frowns, though her heart beats furiously against his (if he even has one; she's not sure how it works with these creatures). "You didn't answer my question."

He raises an eyebrow. "You would've drowned, otherwise," he tells her as if it's the most obvious thing in the world. "Your kind can't breathe down here."

(Down here?)

Her brow goes crooked, uncomprehending. "What do you mean? I don't understand..."

And then, suddenly, she does.

He holds her steady in the water, and she doesn't panic. Instead, she simply stares at him, wide-eyed, watching the slow undulations of his hair in a sea of blue, sunlight filtering down and illuminating the freckles dotted across his face. She glances down and sees the transparent sleeve of her dress billowing lightly against his arm, her skin still her own beneath it.

Her gaze meets his, startled at the revelation. "Why did you bring me here?"

He frowns. "I thought that was what you wanted," he says. "You came to me, after all."

Her grip tightens on his arms. "I don't know what I wanted. I just..." she stops, blushing again. "I just liked to hear you sing."

He stares at her as if she is a lost child. "None of your kind can hear me sing unless they want to," he says, "and usually only in difficult times." He pauses, then adds: "I assumed it was the same for you, princess."

The pink fades from her cheeks, and she withdraws from him a little.

(I wanted it.)

She remembers that awful craving she felt for so long, and though she can see its source now so clearly in front of her - those curious green eyes poring into her in a way that both unsettles and delights her - she realizes that it was not simply the temptation of his song that brought her back.

"I didn't want to hear it anymore," she says, hardly aware of her own speech. "It reminded me of them."

His hands trail smoothly along her arms. "What? Who?" he asks.

Part of her thinks he knows already, but she tells him anyway. "My sister's knocking on the door," she explains. "She used to ask me to come out and play - to build snowmen - but stopped after a while, when I didn't answer." Her eyes tighten. "Then our... our parents died, and she tried again, from time to time," she continues, her face half-lit by murky sunlight, "but I still wouldn't answer her."

A pause. "They died at sea," he guesses (knows), and she nods.

"Yes," she confirms, "at sea." After a moment, she makes the connection: "That's why I heard your song."

"Then you were crying from sadness," he observes pointedly. "Your tears fell like ice."

For a moment, she doesn't know what he's talking about; then, she remembers, and her hand floats up to touch her right cheek lightly. Of course, by then, there's no trace of it left, but by his remark - your tears fell like ice - she knows that he's telling the truth.

"That's my curse—the ice," she clarifies. "I can't control it very well when I'm feeling sad."

(Or ever.)

He caresses his hands in hers, smiling generously. "That is no curse, princess. It is a gift."

She's distracted by the sensuous, otherworldly touch long enough to think she didn't hear him properly - gift? - and then looks at him in disbelief. "It can't be," she protests, and a twinkle of pain stabs at her heart even under this siren's spell, "because it has already hurt someone—my sister."

"A gift isn't always kind, but it always has a purpose," he replies evenly, placing her head on his chest, comforting her. "One day, you will understand yours, just as I came to understand mine."

She recalls him saying something - I was someone once, like you - and then his lips are on hers again, breathing into her, lingering there even after the act is done and her cheeks are flush with life.

She barely manages to speak through the heat that shoots up her body. "What is your gift?" she asks. Collecting herself, she presses: "Who were you, before this?"

He sighs, running his fingers through her long, light blonde locks, long since come undone from the tight braid she normally keeps them in. "That's a story for another day, princess," he tells her, smiling when she looks disappointed. "A long one, at that. Full of sadness and regret, like yours."

She doesn't like that answer. "You said you knew royalty like me... were you one as well?"

His lip twitches. "You're persistent," he comments, "and yes. I was. A prince, in fact—the last in a long line of them." His smile darkens briefly. "Unwanted, as such."

(Unwanted.)

It sounds familiar to her, if for different reasons, and she cannot contain her curiosity. "And how did you become... like this?"

His smile, unchanging, suddenly strikes her as cold. "I begged for death after a shipwreck at sea," he replies. "And then they found me - the sirens - and the rest, as they say," he continues, his lips pealing back into a grin, "is history."

She thinks she'd find that expression handsome, under other circumstances. As things stand, however, it's too aloof for her liking.

"But I thought... I thought that sirens—"

"Kill you? Steal your soul?" he finishes, and chuckles. "Yes, I suppose that's what your kind believes. The reality is quite different."

A thought strikes her, and she glances up at him, surprised. "You... you intend to let me go, then?"

He taps her beneath her chin. "For now."

When she frowns in discomfort, he pauses for effect; as he cups the side of her face, her unhappy expression slips away. "I won't hurt you," he says, and his green eyes gleam beautifully. "Not until you want me to." His words are soft against her unguarded ear. "Even then, you won't feel any pain."

She breathes out a sigh, or something close to that. "Just like your song."

"Yes," he nods, "just like that."

She gives him a curious (and scared) look, but cannot help from leaning closer into his hand, soaking in its strange warmth. "But when will I know when I... when I want you?"

He kisses her other cheek. "You'll know," he tells her, "and you'll come."

She isn't so sure, and he can see the uncertainty in her face—but he merely smiles, drawing her in until their lips are nearly touching again.

"But now it's time for you to go home, princess."

She awakens - not to the sound of waves crashing against the shore like she expects, but to the that of gentle knocking on the door - and she has no memory of how she returned to the castle, and certainly none of how she ended up back in her own bed.

"Elsa?"

The shock of hearing that voice is enough to send spirals of frost shooting from her fingertips, one hitting the door, and she can practically picture her sister recoiling on the other side of it. She clutches her hands to her chest, breathing hard... only to realize that she isn't wearing her gloves.

Her eyes dart around the room, seeking them out from the panic of habit; then, a hazy recollection enters her mind of a pair left by the ocean, slowly being swallowed by the tide, and her heartbeat slows.

She gently lowers her hands into her lap, and looks down at them.

(It is a gift.)

In that moment, they no longer appear only as offending objects capable of great harm. Now, there is something else there.

(And it always has a purpose.)

She curls her fingers into her palms one after the other, mesmerised, and then out again. Her eyes look up at the door.

"Anna?"

A small sound of surprise, and then a long pause—long enough to make her wonder if she's being foolish in feeling hopeful. She gathers up her courage, walks to the door, and opens it.

She's greeted by the tight embrace of her sister, the young girl's sobs muffled against her shoulder. She holds her steady, stroking her red hair (just like he did hers, under the waves), and cannot help but sigh with relief. "Elsa... oh, I've missed you so much!" the girl babbles through her tears, clinging desperately to her older sister.

She adds after a time, in a smaller voice: "Please don't shut me out again."

The princess draws her in closer. "I won't," she reassures her. "I promise."

(One day, I will understand it.)

Her bare hands grip her sister's arms fiercely; she's afraid to let go.

(And I'll know.)

Her breath hitches, and she shudders.

(And I'll come.)