A/N: My followers on Tumblr have dubbed me the Queen of Kristanna Smut. I try not to disappoint.

(Please note that this fic is rated M for strong sexual content. If that offends and/or upsets you, please give this fic a pass. Otherwise, enjoy!)

"Girl in the Mirror"

"They're going to notice I'm missing."

"I won't keep you long."

Anna laughs, light and easy, kneels up on the vanity seat and kisses him, tangling her fingers in the shaggy blond hair at his nape. Kristoff is overdue for a haircut, and it makes him look wilder, less polished, and her blood runs hot.

He slides his hands over her narrow shoulders, down over the stiff bone curves of her corset, and she's glad the maid hasn't yet arrived to tie the stays as he tugs the contraption down and cups her breasts.

"How much time do you have?" he asks, breaking the kiss to trail his lips warmly over her jawline, to the hollow behind her ear, nipping and dipping his tongue lightly against the skin.

"…I don't know," Anna says, and her voice is already breathless. She cants her head to one side, reaches to wrap her hands around his wrists, stroking her thumbs over the thick wristbones as he toys with her nipples, stiffening in the cold evening air. "It's… it's risky."

Kristoff crooks a grin at her, pressing a lingering kiss to her temple. "Tell me to stop and I'll stop," he says.

"I know," Anna says, smiling at him. "But I don't want you to."

"You're gonna get both of us in so much trouble."

"Mm." Her smile widens, eyes dark, as Kristoff moves one hand to slide downward over the flat plane of her stomach, over the lacy fabric at the juncture of her thighs.

"No way you didn't do this on purpose," he murmurs, pulling back from her enough to eye the corset loosened around her ribs, the haphazardly done-up garters and thigh-high stockings. "God, Anna, you're going to kill me, you know that?"

"It's my birthday," she says in a too-sweet voice, eyes fluttering shut on a delicious moan as he flexes his fingers against her. "Just wanted to… mm… dress up for the occasion."

"So, what, you're wearing this for the hundred or so people waiting down at the ball for you?"

Anna keens softly and drapes her arms over Kristoff's broad shoulders, hips rolling smooth and slow as he pushes the fabric aside and his fingers slip-slide deliciously over her. "Just for you," she manages, biting her lip. "Only for you."

"Luckiest man in the world," Kristoff says quietly, wrapping a strong arm around her waist to support her as he curls his stroking fingers into her.

Anna's breath hitches, and she leans against him. "It's just me, remember?" she says, tilting her head back to gaze at him, a smile quirking at her lips, eyes hooded and beautiful.

She's joking, but Kristoff's hand stills against her.

"You don't really believe that, do you?" he asks, and there's something inscrutable in his tone.

Anna squirms and catches his wrist, tries to make him move, but he holds fast.

"Anna," Kristoff says, brown eyes staring deeply into hers, and her heart skips a beat at the intensity within them.

Part of her wants to run. Part of her wants to tear the finely-tailored jacket from his shoulders, throw him back and fuck him senseless.

And part of her wants to wriggle out of his grasp, throw her dress on, hide and cover and pretend that she'd never tried to be, well, anything other than just Anna, never tried to be this coquettish minx silhouetted in lace and silk, everything beautiful and sexy and what was she thinking, honestly…

Anna yelps as Kristoff spins her so her back is flush against his chest, and she starts at the sight of herself in the mirror at her vanity, breasts bared, lips red and kiss-stung, hair disheveled.

She watches Kristoff incline his head to suckle gently at the side of her neck, and she instinctively moves her knees further apart as he begins to thrust his fingers in and out of her in a shallow rhythm.

"Tell me to stop and I'll stop," he repeats, voice quiet, and he catches her earlobe in his teeth.

Anna can only nod, resting one hand against his forearm, feeling his muscles contract as he sinks his fingers more deeply into her.

"Do you have any idea how beautiful you are?" Kristoff asks, pressing his cheek to her temple and moving his free hand to curve around her breast. Anna tries to avert her gaze, but he holds her fast, and her breath is tight and short in her chest as she watches his thumb stroke firm over her pert nipple, sees his fingers twist and glide between her legs.

"I…" The words die in her throat, and she can only watch, helpless, as Kristoff's hands move sinuously over her, and she presses her head back against his shoulder on a tight groan.

Anna starts as Kristoff moves the hand at her breast to gently grasp one of hers, and she flushes deeply, her breath catching as he angles her hand down, as he strokes her fingertips in a slow, circling caress over her nub.

Her eyes fall shut, and he nudges her cheek with his. "No," he says, insistently. "Watch."

She opens her eyes, fingers trembling as she strokes herself in time with the curl and thrust of his fingers inside her, her free hand wrapped tight enough to bruise around his wrist. Her spine arches, curves, hips rolling as she watches, sees herself open and wanting, sees Kristoff's eyes dark with lust over her shoulder, sees the heavy rise-fall of his chest as his breath quickens, as she keens and rocks herself harder against their hands.

"I'm gonna…" she manages to choke out, and with one firm press of her thumb and one hard, deep thrust of Kristoff's fingers she's there, crying out, spine straightening, voice breaking on a sob as she digs her nails into his wrist and comes beautifully around him.

After a long, long moment, as the world rights itself, Anna opens her eyes.

She looks utterly disheveled, legs settled wide apart, hair wild around her shoulders, Kristoff pressing gentle kisses to her temple, her cheek, and she watches as he slides his fingers from her, shining-slick with her release, and brings them to his mouth, watches wide-eyed as his tongue slides over them, feels herself burn down to her toes at the contented noise he makes.

She manages to keep her eyes open as Kristoff tightens his arm around her, nuzzles against her cheek. "No one 'just' would have been able to do that," he says pointedly, and Anna can't help but roll her eyes affectionately at the lazy grin reflected at her in the mirror.

"Okay, you win," she says, resting her hands over his forearms and snuggling back against his chest. She's quiet for a moment, thoughtful, before turning in his embrace, just a little, just enough to place a warm, lingering kiss against the underside of his jaw. "Thank you," she says quietly, eyes warm and soft.

Kristoff affectionately nuzzles her nose with his before leaning down to kiss her. "Happy birthday, you."