"Cisco is standing under the mistletoe. Again," Louise Lincoln says, falling on a chair next to Caitlin. She huffs in exasperation, her eyes narrowing behind her eyeglasses. "I swear, it's like he's not moved for three fucking hours."

Caitlin shakes her head, unsuccessfully trying to hold back a smile. She's sitting by the drinks table nursing another glass of wine in the hopes of forgetting about her aching feet. She has not danced this much since last year's party, and the six inch Manolo Blahnik pumps she's wearing are certainly not helping.

Her eyes skim through the room – a few couples are still dancing, even though it's almost twelve; the live band is tirelessly playing another Christmas song – this time it's a swing version of 'White Christmas' that sounds so warm and charming that Caitlin almost wants to go back to the dance floor, screw her aching feet. But that's the annual STAR Labs Christmas party for you.

It's always an exquisite affair – involving the biggest Christmas tree that can fit the room, most talented musicians, glittering decorations (this year they even have fake snow), and lots and lots of alcohol. Obviously, all the STAR scientists are invited, along with their loved ones, so the party is usually full of laughter and people drunkenly playing charades, or dancing, or generally doing stupid things. Like trying to catch their co-workers under the mistletoe. Or inventing an alternative for the Christmas tree star (don't even ask).

"Please save me, Snow," Louise begs with a pout. "I need to go to the bathroom and he's standing in my way."

"First, I know you're just trying to run away from the party," Caitlin says, and her friend snickers, "second, it's not even that terribly difficult, you know?"

"Oh? Then maybe you should go make out with him yourself if it's so easy for you – oh yes." Suddenly her lips stretch into a wide smile. "Look, Larry's coming with actual bourbon, God bless our chemists."

Caitlin's gaze falls on Dr Wells, who's talking to the guests on the other side of the room, wearing an outrageous velvet suit that certainly shouldn't make him look this good, damn him. The bourbon starts to sound like a splendid idea.

"Okay, finish your glasses, ladies, and we'll fill them with something real this time."

Caitlin passes her empty wine glass to Larry, and cautiously rises from her chair. Her feet still hurt like hell – she really should have brought an emergency pair of comfortable shoes with her – and she takes a few steps to discern if the blisters are as bad as they felt sitting down. They are, in fact, worse, and for a second Caitlin entertains the idea of taking the shoes off and spending the rest of the night barefoot.

"Enjoying yourself, Doctor Snow?"

She turns around, her nostrils taking in the familiar scent of expensive cologne. Dr Wells looks at her smugly, his eyes glinting behind his glasses, daring her to make a misstep.

"Very." She smiles, hopefully appropriately enough – it's hard to maintain the balance between respectful and friendly while being embarrassingly drunk. "These shoes are torturous though, never again."

His gaze wanders down her body in an instant; down her proper black dress, down her stocking-clad legs to her blasted shoes. Her skin prickles under his regard and she shivers. She's sure he notices that too.

"How unfortunate," he says, but there's nothing apologetic about his smile – which widens when he dips his head back. "Look at that, Doctor Snow. The most beloved Christmas tradition."

Caitlin's blood runs cold when she follows his gaze to the mistletoe hanging right above their heads. She looks back to him, wide-eyed and panicked. He takes a sip from his glass, blue eyes crinkling at the corners, challenging. Surely he can't mean –

"That would be highly unprofessional," she says dryly. She can feel her friends watching them from their spot at the drinks table and she straightens her back.

Dr Wells's smirk grows even wider. "That's highly unfestive of you."

The very idea of kissing him – right here, with all those people watching – makes her body flood with warmth, goosebumps rising on her skin. He's maddening, she wants to wipe that smug look off his face and curl her fingers into the lapels of his ridiculous jacket and –

Caitlin takes a deep breath. Then rolls her eyes. "Fine."

She doesn't have to stand on tip toes – this must be the only advantage to wearing those heels – only turns her head to the side and presses a kiss to his clean-shaven cheek.

She draws back, her face feeling too hot, lips tingling as if touched by electricity.

"Merry Christmas, Doctor Wells," she says. There's a promise in the look she gives him.

Dr Wells takes another sip from his glass, then licks his lips.

"Merry Christmas, Doctor Snow."

She returns to her table in a daze, gladly accepting the bourbon and draining it in almost one go. Louise makes an incomprehensible sound from her seat next to Caitlin.

"I can't believe you turned down the chance to snog Wells. Are you sure you're not alien, Snow?"

Caitlin huffs, willing her body to cool down. She can see Dr Wells on the opposite side of the room again, back to doing rounds. There are still so many people there, it seems the night is going to be longer than she expected.

.

.

It's after 2 AM when the party finally starts to wind down. Caitlin helps Louise bundle Cisco and Larry into a cab, then goes back inside under the guise of wanting to help with the clean up.

She ends up in front of Dr Wells's office door, her hand flexing on the handle. She takes a deep breath, her skin tingling with anticipation.

Merry Christmas indeed.

He's sitting behind his desk, tapping furiously at his laptop. He stills when he hears her close the door.

"That thing you did out there? Horrible," she says bitingly, approaching his desk. "How could you?"

Wells takes off his glasses – God, how does she keep forgetting to ask about them? – and smiles lazily. "It sounded like a fun idea at the time." Bastard. "Still does, actually. Well played, Dr Snow."

"You're despicable." She walks around his desk, the clicking of her heels on the floor the only sound in the quiet room. "I'm not sure you've been good enough to get your present."

It's delicious, seeing his smug grin slip from his face, seeing his eyes darken as he looks down her body. Goosebumps rise on her skin again and heat starts coiling at the bottom of her stomach. Caitlin smiles.

"Actually," he says, his voice sounding rough and significantly lower, "I have something for you too."

"Wait for your turn then."

She reaches for the zipper on the side of her dress – her black, knee-length, perfectly respectful cocktail dress – and slowly drags it down. Wells's eyes follow the movement of her hand, leaving a burning sensation on the skin she uncovers. She lets the zip come all the way down, then pushes the dress sleeves off her shoulders.

Caitlin shivers as the dress slides down her body and pools at her feet.

A strangled sound escapes Wells's throat as he takes her in. Her lingerie is red, a lacy bra and panties, a thin curve-hugging garter belt around her hips. Only her stockings are black, to not give anything away.

She straddles his hips and carefully sits down in his lap, her arms curling around his neck. She weaves her fingers through his short hair. It always surprises her how soft it is, no matter how many times she touches it; she wonders sometimes if her brain functions at all when they're this close together. It's as if there's only heat running through her body; electric currents, insistence, and blind, primal need.

His hand is splayed over her lower back to keep her in place; the other slides over the curve of her ass and Caitlin moans in delight. It's excruciating – and delightful – the way he knows her so well, can play her body like an instrument compliant to his touch.

"Merry Christmas, Harrison," she says breathlessly. Their lips meet in a hard, frenzied kiss, tongues sliding together and teeth clashing. She pulls at his hair, and he catches her bottom lip with his teeth, presses down a little too hard. Heat courses through her body.

One of his hands moves from her back and slides lower. He smiles at her, red lipped and hungry, when they come up for air. He pushes his fingers under the lace of her panties.

"Merry Christmas, Caitlin."