Title: Ying and Yang

Summary: Beckett finally realises what Castle was talking about when he mentioned Ying-Ying being a name for a panda. Minor spoilers for 1x09 (Little Girl Lost). Set post-Deadpool. This fic was written for Manuxinhace's challenge (fanfiction .net/s/7382548/1/Challenge).

Rating: M - Language, adult situations.

Disclaimer: The usual. Sadly.

Author's Note: So, this one has been brewing for a little while now. My Beta finally convinced me to post it up in chapters, rather than trying to complete the whole thing first. I was hoping to avoid having another multi-chapter fic on the go, but she was right (she usually is!). To all of you who are sticking with me for the next chapter of Layers, I can only offer the following: I'm so sorry it's taken me so long to get it updated! I didn't mean for it to be so long a break, but I've had a bugger of a time getting it to where I want. It shouldn't be too long now, folks. Anyways, please read and review...

Kate Beckett was restless. No, she was tired and cranky, and not being able to sleep was just pissing her off even more. She shifted in her bed again, adjusting her pillow and rolling over so she wasn't touching Josh at all. Wriggling down, she finally seemed to find a position comfortable enough to allow her to doze off.

As if I'm going to get any decent sleep now, she thought bitterly, the bedside clock reading 3:15am. Sighing, she closed her eyes, willing herself to sleep.

The incessant blaring of her alarm shattering the pre-dawn quiet, Beckett groaned and rolled over, slapping the 'off' button and shuffling her way to the bathroom, turning the shower on as she stripped off her singlet and panties. Stepping into the steamy water, she allowed her head to fall against the cool tiles for a moment, letting the heat soak into her, gradually bringing her closer to waking.

As she absently performed her morning cleaning ritual, her mind began to wander, trying to place exactly what had been nagging at her for a while now. She had been getting progressively more easily irritated over the last few months, and it was starting to show. It wasn't anything that she had really noticed at first, but lately the smallest things seemed to set her off, and there didn't really seem to be any main factor responsible. Their cases hadn't been particularly difficult lately, so that was out. Castle had been (relatively) quiet, his inputs insightful, with not even a mention of a three-letter government agency. She smiled slightly recalling his words from last night as she signed off the charge paperwork for the man they had in lockup.

"There now, Beckett, that wasn't so hard, was it?" Castle's cheerful grin might have sounded off the cuff, but the mischievous sparkle in his eyes gave the words a whole different layer of subtext. She paused, quickly filling out the last required signature on the forms and put her pen down. Turning to face him, a half-smile formed as she bit her lip, a knowing look on her face as she saw his eyes dart to her mouth briefly. A forced tone of casualness in her voice, she teasingly replied,

"Oh, I don't know, Castle… Sometimes I'm a fan of easy…" A sultry smirk tugging at her lips, she couldn't help but let a small chuckle slip out a she saw her words briefly rob the author of a response, his eyes going vacant for a brief second as he contemplated the words 'Kate Beckett' and 'easy' in the same sentence. A slow, wicked grin crept onto his face as he leaned forward and countered, his voice a velvety, bass rumble,

"Why Detective, I had no idea you were so… naughty." There was something about the way he said the last word, it… suggested. Nothing overt, but somehow those two little syllables conjured a barrage of impressions in her mind: the flickering of candles, sweat beading on skin in the half-light, the scent of new leather, and a throaty, wicked chuckle she hadn't heard herself use in years. Eyes locked on each other, Kate could feel the thoughts in his mind, almost able to see the images he was conjuring in his imagination. The heat of the moment, only heightened by his subdued voice, caused her stomach to tighten, a delicious tingle spreading through her. Unconsciously, she leaned forward, her elbows resting on her desk, fingers absently toying with a curl of her hair as she studied his face. Trying to conceal the fact that she was having a hard time controlling her breathing, she reached forward. Their faces only inches apart, she placed one finger under his chin, tilting his head back slightly, her lips brushing his ear as she whispered to him, repeating the words she had said all those years ago.

"You have no idea…" Leaving him dumbstruck once more, she picked up her bag and walked out, putting a little extra swing in her hips, just for good measure.

Trying (and failing) to convince herself that the flush in her cheeks was from the heat of the shower and not from recalling the innuendo-laden banter with her partner, Kate mentally crossed Castle off her list of things that might be the cause of her irritation. In fact, she realised, he might have been providing the only points of relief from her steadily worsening moods. Sighing, she turned the water off and stepped out of the tub, reaching for her towel.

Making her way into the bedroom, she pulled open her drawers, rummaging for something to wear, absently noting the bed was empty. A small frown creasing her face, she picked up her cell phone from the bedside table, and saw she had one new message. Opening it, she saw that it was from Josh, the time-stamp reading 4:30am.

*Babe, got called in to cover an early shift. Pulling a double, so not sure when I'll get out.* Sighing in frustration, Kate threw the phone onto the bed, wondering how many times she needed to tell her boyfriend she hated being called 'babe'. It made her feel like some tacky bimbo, the sort who giggled over quarter-backs. Deciding that there was no real need to respond to the message, she continued getting ready.

Toweling her hair dry as she walked into her kitchen, Kate saw that Josh had left a cup on the bench for her. Glancing into it, she noted he had fixed her the ingredients for coffee, minus the hot water. She smiled, grateful for his consideration. Flicking the button on her kettle, she made her way back to the bedroom to get dressed.

Hearing the click of the kettle finishing, she walked back into the kitchen, tucking her necklace into her shirt. Looking at the clock, she winced slightly, knowing that she'd need to rush if she wanted to get to the precinct on time. She quickly poured the boiling water into the waiting cup and added a splash of cold. She took a quick sip and immediately spat it into the sink. Frowning, she looked at the offending cup of liquid, her glare almost sufficient to bring it back to the boil.

She assumed that Josh had made the drink the same way he would for himself. Full-cream milk (which she had in the fridge only for use with hot chocolate), and three sugars. She wrinkled her nose at the thought, the after-taste still curling her lips. He must have used the last couple of spoonfuls of instant coffee powder from the tin at the back of the cupboard. She'd been meaning to throw it out for months now, that stuff wasn't even fit for guests she wasn't fond of, although she could imagine that Josh would probably have barely noticed it, the cafeteria coffee at the hospital ranking a shade below even the monkey-pee-in-battery-acid the precinct used to have, before Castle brought the coffee machine in. Pouring it down the drain, she rinsed the cup briefly, before grabbing her bag from the bench and heading out. Coffee would have to wait until later. She sighed, a headache already beginning to form. She just knew today wasn't going to be a good one.

Fuming, Beckett flung herself into her chair, her fingers angrily stabbing at the keyboard as she logged in to her computer. Her morning had gone from bad to worse on the drive in: traffic had been a nightmare, her headache had been upgraded to a splitting migraine, and to cap things off she'd been slammed into the wall of the elevator by a meth addict under arrest on her way to the Homicide floor.

Now tired, pissed off and sore, Beckett was not really fit for human company, let alone a busy precinct. Both Ryan and Esposito got nothing than a grunt in response to their morning greetings. Wisely deciding that discretion was the better part of valour, the other detectives felt that perhaps this morning would be a good time to catch up on their own paperwork, quietly, and to leave their boss alone until the thunderclouds had departed somewhat.

The minutes seemingly dragging past at a glacial pace, Beckett glanced at the clock briefly, her stomach suggesting that perhaps it might be time for something to eat, and washed down with a hot, caffeinated beverage. Before her irritation could manifest itself further, a paper bag and coffee-cup were placed on her desk. Startled from her funk, Beckett looked over to see Castle flopping down into his chair, his own coffee empty already, the cup making a gentle arc as he tossed it expertly across the desk to land neatly in the garbage bin near her desk.

His enthusiastic antics finally tipping the scales of her mood beyond tolerable, she snapped at him.

"Castle!" His eyes snapped up to her, innocence on his face. "Do you have to?" She saw shock, confusion and hurt flash across his features in a fraction of a second, before they were ruthlessly squashed by his poker face. Carefully neutral, he took a quick inventory of her, noting the tension in her posture, the fire dancing in her eyes, the slight narrowing of her eyelids, all of which spoke of a temper only barely reigned in.

He stood up and left her desk, heading for the break room without a word. Beckett turned back to her monitor, her left hand picking up the coffee cup on auto-pilot. The moment the coffee slid down her throat, and the happy sigh eased it's way past her lips, she froze, appalled at herself. Replaying the last few seconds in her mind, she realised that her partner had just brought her breakfast and coffee the same way he did every day, and she had just ripped into him for it, without even thanking him for perhaps the only thing that had gone right for her the whole damn morning: her coffee. The hot sting of guilt flashed through her, and she was halfway through getting out of her chair, when Castle returned. Extending his hands, she saw that he had a cup of water for her in one, and some ibuprofen in the other. Her stomach twisted as she realised that despite her treatment of him this morning, he had noticed the fact that she had a headache, and fetched supplies to fix it, even as she had been chewing him out. Her cheeks flushed, Kate quickly downed the tablets, followed by the water. Still standing, she walked around her desk towards an empty interview room. Passing Castle, she looked back over her shoulder at her partner, saying quietly,

"Castle? A word please?" A little startled at the hesitant tone in her voice, Castle followed her, his alarm increasing slightly as she allowed him to enter the room, then closed the door behind him. Turning back to face him, Beckett drew in a quick breath, bracing herself as she spoke.

"I'm sorry, Castle," She spoke quickly, her voice quiet as she looked up at him, hands thrust into her jacket pockets. "You didn't deserve that, especially not first thing in the morning. I snapped at you for no reason, and I'm sorry." Taken aback, Castle smiled at his partner, the sting of her earlier words eased by her apology.

"It's okay, Beckett-" He managed to say, before she cut him off.

"No, Rick, it's not. I've been getting more and more bitchy lately, and I've been taking it out on you guys. You don't deserve it, and neither do they. I need to figure out what's wrong before I go crazy here." She sighed, running one hand through her hair as she forced herself to relax a bit. "Today has just gone from bad to worse, Castle. So far the only thing that hasn't pissed me off is our coffee, and I still managed to screw that up." Castle could see the tension starting to build in her again. His face softened as he looked at her, wordlessly acknowledging her apology.

"Maybe when the case is done, take a couple of personal days? Get out of town and clear your head for a bit?" He suggested, knowing well the value of a couple of days away from everything. Beckett thought for a second about the idea, the more she pondered it, the more attractive it sounded. A few days out of the city, she could even visit her dad for a decent catch-up. Feeling much closer to being a rational human being once more, she replied.

"Thanks, Castle, I might just do that. I think I could do with a break." Unlocking the door, they exited the observation room, ready to tackle the case again.

A/N: honestly folks, i have probably the next three chapters already written up, just needing a little polishing before I post them, so you shouldn't have too long to wait for updates. In other news, I blame Manuxinhace for the bunch of other fic ideas I'm now going to have to go and write up for the challenge... ;-P Thanks hun!