A/N: It's been a while! Story based off a tumblr prompt that will be posted at the end of the story :)

Water Shortage

Kate all but collapses onto her couch as soon as she's through her apartment door, the plastic bag of Chinese takeout barely managing to land on the coffee table as she throws it.

It's not even late, barely bordering on six in the evening, but she blames her stubbornness as the reason for her exhaustion. Working non-stop for almost two full days hadn't been the smartest idea but she couldn't help it when leads for her current case had started sprouting at every corner. Her hard work and resilience had led her and the boys to narrow their search down to two possible suspects but Montgomery had sent her home before she had a proper chance of interrogating them.

She had offered up a fight but once her stomach had started growling and the constant headache she'd been harboring since early morning intensified, the exhaustion began to make its presence known and Kate had bowed out of the precinct with her dignity still intact.

She had stopped by her favourite chinese takeout place on the way home, picking up an order that included both hers and Lanie's favorite dishes.

It was the second Saturday of the month, which usually meant a girls night for Lanie and Kate. One that often included wine, reruns of Temptation Lane and talk of their love life (or lack thereof for Kate). It had been a while since Kate had last caught up with her friend; lengthy cases had often gotten in the way of the friends having a catch up.

Kate was exhausted but she wasn't planning on canceling on her friend even though Lanie would understand. Because a relaxing, girls night was exactly what Kate needed after a long week.

There's a knock on her door and Kate sighs, eyes sliding open though she can't remember when she had closed them.

Huh, Lanie's here earlier that she expected.

Kate pushes up slowly, her muscles tight and wired from the long day. It's a reminder that she should probably get back into her yoga routine.

She makes her way to the door, not at all fussed with her appearance. Lanie has seen her in worse attire than her crinkled blouse, creased trousers and messy hair. She reaches for the door handle, fingers curling around the smooth metal as she pulls at the door.

"I didn't know you'd be here so early," Kate says with a prepared smile.

Her smile morphs into a frown as she notices who's standing at her door, someone who is definitely not her M.E best friend.

"Expecting someone, Detective?" The visitor smirks, leaning one hand against the doorjamb.

Kate rolls her eyes and crosses her arms, raising an eyebrow at the man standing at her door.

"What do you want, Castle?" Kate asks, only just managing to keep the groan out of her voice.

"I thought it was obvious," Castle responds, lowering his voice to a deep tone. His eyes hold her own for a moment before they deviate, running up and down her body slowly, lingering on the exposed skin of her collarbone before trailing down to her waist.

His burning gaze sends a flare of heat through Kate's body and she prays that the evidence isn't showing on her cheeks.

It's all too familiar. The way he steps towards her, crowding her space as his breath fans across her cheek. It takes her back to memories from almost a year before, when her and the man standing in front of her were more than just awkward neighbors – ex-friends with benefits.

Meeting Richard Castle had been an accident. After crashing, (quite literally), into him as she was moving into the apartment building, they had taken an intense disliking to each other. That was until earlier in January the time of year that Kate hated the most. Kate had found herself in a bar that was nowhere near her apartment but close to the precinct. After numerous shots of vodka that had eventually stopped burning, Castle had sat down in the seat next to her, almost as drunk as her.

It was her that had taken his hand, dragging him out of the bar and only just managing not to stumble as she clambered into a cab. She had pulled him in immediately after her, smearing her mouth against his and pressing him against the cab door with a plea for him to help her forget.

Their nights of pouring their problems into each other's bodies had lasted for only six months before things had gotten complicated. Waking up to an empty apartment had turned into waking up to coffee and pancakes. Goodbyes had turned into 'see you tonight'. Quick and fast had started to morph into slow and sweet.

Yet underneath all the slow kisses and countless coffees, the cocky and arrogant Castle was still there, the freshly signed divorce papers protecting his heart. In some twisted form of role reversal, Kate had found herself wanting more, no matter how scared shitless she was of their current predicament

The demise of their rela– arrangement had been her fault. She had been the one to end it after all.

Castle steps forward and the proximity drags Kate out of her thoughts.

Her retort dies on her lips. He's barely an inch in front of her, so close that she can practically feel the heat radiating from him.

"I want," Castle repeats in a whisper, leaning down so his mouth is parallel to the shell of her ear. "To use your shower."

He wants to – oh. That is so not what she expected him to say.

Before she can object, Castle's picking up a duffel bag that she hadn't noticed and striding through her apartment.

"Nice place," he comments, as if he hasn't stumbled through the door on late nights with her. As if he hasn't pressed her against the flat surfaces of her apartment and touched almost everything in her apartment. Herself included.

A scoff escapes Kate as she closes the door, not even bothering to make an attempt at getting him out of her place. He's always been a persistent person, so there's no point in even trying to get him to leave.

"Expecting company?" He questions, eyes flickering to the takeout on the coffee table. There's a hint of annoyance swirling in his eyes and if Kate didn't know better she would've thought he was jealous. But she did know better and there was no way Richard Castle could be jealous of the company she may or may not have been expecting.

"That's none of your business," Kate huffs, crossing her arms over her chest.

The arms over her chest is something Castle picked it up a while ago. It was a defensive position for her, one she usually resorted to when she was on edge or guarding herself. Though he loves to make her squirm, he's never enjoyed being the reason for her to guard herself and right now he seems to be doing just that.

"Why do you need to use my shower anyway? What's the matter with yours?" Kate asks after a moment, seemingly fed up with the soft looks he was shooting her and the uncomfortable silence.

"Ah right," he starts sheepishly, scratching the back of his neck. "A Derrick Storm experiment didn't go to well and now I have to wait a few hours for the repair guy to fix the damage"

"I'm not even going to ask," Kate interrupts, amusement displayed across her face. "What about the guest room en suite?"

Castle fidgets. "It may or may not have been used for the second Derrick Storm test trial. Anyway," he continues, sending her an annoyed glance. "I have a date tonight and I need to have a shower before I go."

For some reason, (or a reason that she doesn't want to admit), Kate's heart plummets.

She tells herself that they were never anything serious. Nothing more than a few pancake breakfasts after one of their many meaningless nights and stolen kisses that left both of them wondering if they could make something work. But she's lying to herself and she knows it.

It's only been 3 months since their 'arrangement' had come to an end and he's already moved on. She pretends not to notice the heaviness in her heart, is horrified by the stinging behind her eyes.

She has no claim to him and no right to be jealous or upset.

Castle clears his throat as the tension in the apartment builds, turning the air into a thick cloud that forms a lump in the back of Kate's throat.

"So, shower's in the same place, right?" Castle assumes.

"Yeah, go ahead," Kate sighs, eyes avoiding his.

She waits until he leaves the room to flop down onto the couch with a disgruntled huff.

Lanie knocks on the door a half hour later and Kate can still hear the shower running.

She had completely forgotten about her girls night with her friend. The Chinese takeout is cold on the coffee table and will need to be heated up but Kate's more worried about the man occupying her bathroom who seems to be taking his time in the shower.

"Hey Lanie," Kate greets once she opens the door and is certain it's the M.E. She's thankful that her voice is level.

Her silent prayers of hoping her friend doesn't hear the running shower is a lost cause because as soon as Lanie steps into the apartment she automatically turns on the detective.

"Were you just about to have a shower? Because I can heat up the food while you go," Lanie suggests, shrugging off her coat and placing the bottle of wine she brought on the counter.

"Oh no, it's fine," Kate replies quickly, a bit too quickly if Lanie's look is to judge.

Lanie raises an eyebrow at her speedy response. "Why don't you go turn your shower off then?"

Kate avoids both the question and her friend's suspicious eyes, stepping around to the kitchen counter.

"So, how 'bout some wine?" Kate deflects, shifting uncomfortably as she reaches for the bottle.

"Kate Beckett," Lanie starts in a tone that Kate knows isn't good. "Is there somebody in your shower?"

Her silence is enough of answer for Lanie, who grabs the wine and glasses before pulling Kate to the couch.

He's already finished in the bathroom after taking more than double the time he usually takes. But the space is familiar and comforting and it has Kate's touch everywhere he looks.

He's supposed to be drying his hair but he can't, not when little momentos that scream Kate Beckett are scattered over her bathroom. It's comforting to know that she still uses the same cherry shampoo and vanilla body wash. The scent was perfect for Kate Beckett, just the right mix of sweet and enticing.

He misses her alluring scent and her cute morning routines she usually did in the morning.

He misses her.

It's his fault whatever they had ended in the first place. He was too caught up in the playboy image, the burden over his divorce from Gina. He was too young and stupid to not see what was in front of him and regrets it every time he sees her in the lobby or elevator. He misses her.

Castle realizes he's been in the bathroom for almost an hour when he checks his phone, way too long for him usually. He's surprised that Kate hasn't started banging on the door, demanding for him to get out of her apartment, until he realizes that there are a pair of voices talking.

He can't distinguish them, except for Kate who's currently talking. As selfish as it sounds, he hopes her company isn't someone she's dating. He doesn't think he could see someone else making her so happy.

An idea springs into his head, one that's reckless, stupid and exactly something he would think of.

"You were right, Kate," Castle says as he enters the lounge, drying the ends of his hair with a towel.

Both women turn as he walks in, bag slung over his shoulder. Kate gapes as she takes in his appearance, his – shirtless appearance. He's only wearing a pair of light washed jeans that are slung low across his hips, the band of his briefs visible as he moves. His torso is bare, revealing a chiseled chest and toned abdomen to the women.

"Oh, hey Lanie," he greets, heart lifting when he realizes Kate's company is none other than her best friend.

"Castle," Lanie nods, eyes raking over his bare torso.

"The shower really did make me feel better," Castle announces, walking over to the pair of wide-eyed women.

Kate glares as he approaches, shooting him a look that could make a mafia boss cower. He knows that she's probably going to throw something at him if he does what he's thinking but he can't help but make her squirm. She's adorable when she's flustered.

"I had a great time," he whispers, dropping his voice low. He knows for a fact that Lanie is absorbed in the bubble surrounding him and Kate, can hear every word that he's saying even as he makes it out that the words are just for Kate. And to make the detective blush even more he leans in, splaying his hand at her waist and presses a delicate kiss to her cheek.

"Thanks for letting me shower and everything," he adds on as he pulls back. Kate's eyes are wide and she seems almost frozen. Her immobile state lasts a second before she's back to giving him a murderous glare, slim fingers curling around his wrist that sits at her waist.

"Excuse us, Lanie," Kate grits out, standing up a dragging him with her.

They both notice how similar the situation is to their first night back in January, but neither of them comment on it.

She manages to suppress the urge to shove him out of her apartment, instead 'lightly' urging him out and slamming the door behind them.

"What the hell are you playing at?" She hisses, shoving both palms against his chest. The heat from his bare skin burns at her palm and she flinches as the fire scorches her hands.

"Relax, it was a joke," Castle assures with a laugh, amusement dancing in his eyes and a smirk twitching at the edges of his lips.

Kate scoffs. "Some joke it was, Castle. Were you trying to humiliate me to death?"

The glare she fixates on him is enough to make him avoid her eyes, instead trailing over the patterned carpet beneath his feet.

"Honestly Castle," she continues, exasperation leaking from her voice. "I allow you to use my shower and how do you decide to pay me back? You humiliate me in front of Lanie, who of course! Is going to want to know every detail about a story that doesn't even exist."

Her rant continues and now she's pacing, venting out her frustration through harsh spat words and extravagant hand gestures. Castle rolls his eyes, taking a quick step forward to catch her in the middle of a turn as she plans to pace the other way.

His hand lands at her hip, the heat splaying over her side and searing her skin through the thin fabric of her t shirt. She startles at the close proximity, the way he pulls her closer until his chest is flush against hers. But it isn't him who initiates the kiss, he's not the one who tip toes and sears his mouth against hers.

It's Kate. It's all Kate.

She presses her mouth against his, surging against him as she rises on her tip toes. The first touch of her lips is branding, a welcoming and familiar burn that leaves him begging for ice and more of her at the same time.

But Kate Beckett's always been ice. Always been the one to sooth the burn, yet ignite it at the same time.

He groans when she slips past the barrier of his lips, eradicating the wall of his teeth with a quick sweep of her tongue.

Castle takes the hand from her waist, using both palms to frame her face and deepen the kiss with even more fervor. He walks her back, continuing until her back hits against the wall next to her apartment door.

She gasps when his lips caress her jaw, trailing down until he reaches her pulse point and just hovers there, lips feeling the beat of her.

"Castle," she gasps on a breath, head falling against the wall, eyes slipping closed.

"I missed you," Castle murmurs, lips leaving her neck and pressing a sweet kiss to her lips.

"Missed you too," Kate replies with a low, breathy voice. She only prays that her heart stops beating at a hundred miles an hour, prays that Lanie hadn't heard – shit, Lanie.

"Castle," Kate whispers, pressing a hand against his chest and pushing him away. The heat from his bare skin is welcoming this time.

Regret and disappointment shines bright in his eyes, and he opens his mouth ready to apologize she's sure. Before he can continue she holds a finger against his lips, silencing him.

"Don't apologize and say you're sorry because I'm not," she admits. She's surprised her neck isn't hurting from the whiplash of emotions she's succumbed to.

Kate's eyes trail across his bare chest, moving down until she notices the fancy watch on his wrist. One that she knows he only wears for special occasions and – a date is a special occasion, isn't it?

"But you should go," Kate says loudly, feigning her confidence before it threatens to leave her altogether.

He looks astonished at her sudden change of heart and she doesn't blame him. She's just a roller coaster of emotions today.

"Enjoy your date, Castle," she swallows out, watching at the surprise slowly fades into understanding.

"My date?" Castle parrots, watching as Kate avoids his eyes. "I'm sure Mother and Alexis won't mind if I'm late once I tell them the reason," he finishes with a smirk.

"Martha? Alexis?" Kate stutters, trying and failing to keep the surprise out of her voice.

"You didn't think I could get over the Kate Beckett that quickly, did you?" Castle asks amused, wrapping a hand around her wrist.

"No, it's just–"

Castle pulls her against him with a laugh, framing her face with his hands, thumbs brushing at the sharp bones of her cheeks.

"There is no getting over you, Katherine Beckett," he whispers, dipping down to engage her in a deep, long and slow kiss.

He pulls back all too quickly, leaving Kate with flushed cheeks and an urge for more. And he doesn't stop backing away from her even after he picks up his duffel bag.

"I'll tell mother and Alexis you say hello," Castle states, trailing down the hall, still shirtless but armed with his bag and a smirk. "And I'll see you again – soon, Kate."

"Castle," Kate calls, just as he's stepping into the awaiting elevator. She bites her lip, hoping the blush isn't noticeable on her face. It obviously is from the way he's smirking at her.

"Come over tonight?" She asks, eyes alight. "I think I could use a shower tonight."

"My shower's broken but I've got a date tonight could I possibly use your shower please?" "Oh sure (neighbor that I've been crushing on for the past six months) of course you can use my shower to get ready for your date (fuck fuck fuck)"

I altered the prompt a little but I hope it was okay!

K