"What are you doing, Castle?" He could hear the amusement in Beckett's voice, heard the door click shut behind her again, as she reentered the room, but from his vantage point, he couldn't see her.

"Dropped my pen," he said, smiling as she chuckled. Her chair scraped as she pulled it out, and now he could see her.

Or rather, he could see her legs.

Fuck.

Those were nice legs.

Legs for days.

He swallowed, frozen to the spot beneath the desk; he couldn't have moved if he'd wanted to because really, well - it wasn't like he'd never seen legs before, didn't even think he was that much of a legs man, but Beckett's legs - fuck.

No. He would have to stay where he was a moment longer, get control of himself, and then-

He shook his head, exhaling as he kept his eyes glued to her legs because-

Because why? Why was she even wearing a skirt, bare legs, today? Of all days?

"Desk duty, Castle," she'd told him when he'd gaped at her this morning, handing her coffee over dumbly. "It's a warm day, and I'm not leaving the precinct, figured I'd dress down for a change. Besides, you don't usually stick around when we're prepping for trial, you can go home."

He'd shaken his head. Go home, when Beckett was in a skirt, her legs indecently - and oh so fucking decently - naked? Not an option.

And now here they were, closeted in one of the conference rooms, just the two of them, Esposito and Ryan mercifully off for the day.

He watched, entranced, as she slid into the chair, shifting it forward so that she was closer to the table now. The skirt fell just above her knees, a little higher now she was seated, and rather than cross her legs as he'd expected, she sat casually and he could-

He couldn't.

No. He blinked, trying to tear his gaze away. He could not - would not - look up her skirt.

He looked up her skirt.

"You doing okay down there?" Beckett asked, amusement still in her voice, and did she realize he could see her panties? The scrap of black lace, just a glimpse, but if he wasn't mistaken she was wearing a thong and dammit, he was ruined.

"I'm, uh- yes," he squeaked.

He inhaled, trying to get a grip on himself. He was an adult, dammit, and he'd seen both legs, and underwear, before. Many times. So very many times, in fact.

He shook his head.

It didn't matter.

These were Beckett's legs. Beckett's underwear.

And she'd just moved, just a little, and now…

Now he had a better view.

She wasn't doing this on purpose- or was she?

Because now - he offered up some kind of prayer to any god that was listening - it was most definitely quite clear that she was wearing a thong. And that-

He squeezed his eyes shut, but he couldn't unsee it.

There was unmistakable evidence that she was aroused.

"I can see your panties." The words were out of his mouth before he could stop them, and he felt his cheeks flush hotly. That settled it, then. This was their last case, and maybe their last meeting. The sexual harassment suit would follow any moment, but even with a lawyer as good as his-

His train-wreck of thoughts was interrupted as Beckett laughed, a low, sexy timbre, before speaking. "I know."

And damn, if she didn't open her legs a little wider.

She shifted in her chair again, sliding a touch closer to the edge, closer to Castle. Unable to stop himself - knowing if she didn't want this she was well equipped to stop him - he crawled forward, placing a tentative hand on her knee.

And her legs fell open.

The scent of her arousal was unmistakable now, and he slid his right hand up her leg, brushing a thumb against her core and eliciting a soft sigh from her. Encouraged, he slipped his hand beneath her thong, his eyes closing of their own accord at the evidence of just how wet she was.

She moved again, right on the edge of the seat now, and he swallowed, taking a moment to try and understand that this was real, this was happening, and this was Beckett, before pushing her underwear aside and bringing his mouth to her clit.

She moaned again, and emboldened, he slid first one, then another, finger into her center, his tongue working her as he sought to evoke another sound from her. Rewarded with a sharp cry, he lost himself to the ecstasy of her taste, the feel of her slick around his hand and on his mouth.

Impossibly hard inside his jeans, his cock throbbed, and he all but ignored it, concentrating first - and only - on Beckett's release as he worked her higher. His eyes open again, he watched as her hands gripped the sides of the chair, her knuckles whitening as her breathing became shallower, and he gasped with her, curling his fingers within her as she clenched around them, his tongue flat against her clit as she fell apart under his ministrations.

He brought her down gently, almost losing it himself as she whimpered and he looked up at her face for the first time since this had begun.

Her eyes half closed, she relaxed into the chair, her expression one of bliss, and he withdrew his fingers from her, determined, even as he did so, that this wasn't the last time this happened.

"Get up here, Castle," she commanded, and he crawled out from beneath the table, suddenly all too aware than the blinds on the conference room were half open, and his plan - to kiss her senseless - would be far more visible now he was no longer hidden by the desk.

Before he could march over to the window and draw the shades, Beckett was standing and a small smile played on her lips. Then her expression masked over, business as usual written all over her face, as she strode toward the door, her hand light on the handle as he asked, "where are you going?"

She shot him a look he couldn't quite interpret, as she said, "shower, Castle," turning the door handle as she made to exit the room. "You coming?"

He nodded, scrambling to follow her.

God, he hoped so.