Ahem, Hallow's first attempt at Caskett smut! Read at your own risk!

This is way different than what I usually write so I hope you guys think it turned out okay.

This is slightly based off the promo pictures from 3x16 where it looks like Beckett and Castle are in a quarantine. Upon seeing those pictures, the topic of decontamination showers popped up on twitter and as soon as the idea was mentioned, it stuck into my head until I started considering writing it.

I really didn't expect it to turn into this monster of a fanfic, I'm pretty sure this is the most I have written in a day, ever.

I do NOT own Castle.

Warning: SMUT Rated M for a reason!

"Ugh the nerve of that guy! Sending us all the way out here to check on a storage unit that is going to end up being completely useless. We aren't going to find anything out here, you know that right? It's too easy, there is no way our killer would be stupid enough to rent a storage unit under his own name, it's gotta be a coincidence." On and on Castle complained about the lead they were following as they walked towards the storage unit rented to the man they knew was their killer, but since they had no solid proof, they couldn't arrest him. Not to mention the small fact that they couldn't actually find him.

"Yeah, I know. But the FBI has this case now, we have to follow their rules. Let's just check it out real quick then we can head back."

"Yay, then he'll send us on yet another bogus lead." Castle grumbled, sounding completely unenthusiastic about the prospect while Beckett rolled her eyes and started unlocking the first of the multiple locks that were on the storage unit. Normally she would be irritated with the FBI taking over her case, but this time she didn't really care, she just wanted to get this over with so she could go home.

Of all the days he could have picked, Josh had picked this one to show up at the precinct, just to tell her that it was over between them. If she was being honest with herself, she knew it was bound to happen soon, but that didn't mean that it didn't hurt any less.

It didn't help that she knew exactly why he broke up with her, and that the exact cause was currently looking over her shoulder while she undid the last lock.

"So writer boy, what do you think is going to be in here?" Beckett asked, pausing to see what he said before she lifted the storage door.

"Hmm, probably musty old books and childhood memories that someone has stashed away and likely forgotten about. In other words, something that has nothing to do with our case at all." He bent down and grabbed the handle of the door with her, and together they pulled the sliding door up, revealing a bunch of boxes.

With a detonator attached to them, that was attached to a cord on the door.

They realized it at the exact same moment, turning towards each other and grabbing the other's arm, running as fast as they could away from the storage unit, but they only got a few steps before it went off.

There was a loud boom, but there was no fire just a large gust of wind that sent them to the ground, covering them with a shimmery silver powder.

Nearly immediately after they inhaled the powder, they were out like a light, sprawled out on the hard concrete with their hands still clasped together.

That's how the special agent in charge of this case found them an hour later.

The next thing Castle knew, he was being pulled roughly up from his, strangely comfortable, position on the ground by two men in white hazmat suits.

"What's going on? Where is Beckett?" They didn't answer him, just kept dragging him through various closed off areas until they finally brought him to what looked like a white plastic greenhouse.

They opened the door of the greenhouse looking building and pushed him inside. The door had just barely shut when they started pulling at his clothing, taking them off and shoving them into a bag labeled with the bio-hazard mark.

"Hey, hey! Getting a little personal there don't you think? Sorry fellas, but I don't swing that way." He said when they tried to take off his boxers, but they didn't appreciate his humor and within seconds, he was butt naked and being pushed under a cold stream of water from a shower that was apparently built into the plastic greenhouse.

Without another word the two men walked out of the plastic building, shutting and locking it on their way out. They quickly walked over to what was deemed a non-contaminated area where the special agent in charge was.

"They are in the showers now, what are your orders, sir?"

"Whatever it is, it doesn't seem to be harmful and we know this isn't an airborne contagion so as long as those two are in a contained area, it can't spread. Our main priority is to catch this guy, and now we have some strong leads, we'll worry about them later. At least this way they will be out of my hair." The special agent turned on his heel to go investigate the case, leaving the two men behind.

"Don't you think we should get them some clothes?"

"Boss, said don't worry about them. So don't worry about them."

"Yeah, you're right. Let's go catch this guy!"

Assuming that they wanted him to take a shower to get rid of whatever that powder was, Castle quickly did so, washing as best as he could with no rag or soap of any kind. He was just about to turn around so he could let the water run over his back when he heard a voice speak up from behind him.

"Do not turn around, Castle. I will hurt you."

There were quite a few things that jumped into his mind at the voice: That it was Beckett's voice. That she was in there with him. That he was completely naked in the same room with her. And most importantly, the logical side of his brain pointed out that she most likely had the same thing done to her that they did to him when he was forced into this room. Which meant she was most likely naked too. Naked. Together. In a room that consists only of a really huge shower. Naked. Naked.

"B-Beckett? What's going on?"

"Apparently they quarantined us because of that weird powder that was in that storage unit." She said while Castle was desperately giving himself a lecture on the importance of not thinking about his partner being naked, but it wasn't really working.

"Oh god, what if it's some kind of flesh eating alien virus that our killer found and was going to use in his next bomb?" Freaking out because of the scenarios running through his head, he started scrubbing his body frantically.

"This isn't The X-Files, Castle, and we seem to be fine."

"Yeah well, I'm not taking any chances, you showered too, didn't you?"

She hesitated just a second too long. "Yes."

"What if it just hasn't affected us yet? What if we can get rid of it by showering?"

"I'm not moving."

"If you don't do it willingly, I'm coming over there and dragging you under the water, and I can't guarantee that I won't look." She would hate him forever if he had to do that, but if it was a choice between her hating him, and her dieing because of whatever they had them quarantined for, he would always choose the first option.

She laughed at him. "I'd like to see you try, I'd take you down."

He just smirked at that. "I'm sure you could and would, but that would require touching which would end up with us in an even more embarrassing situation, given our lack of clothing. If you would just wash the stuff off you, we wouldn't have to go through all that. Unless of course, you are wanting to use that as an excuse to have your wicked way with me, in which case I'm all for it."

"In your dreams, Castle."

"Actually, I've never had a dream quite like this before. I did have one where we were-"

"Just shut up and move away from the shower so I can use it." She stood up from her place next to the wall behind him and waited until he moved towards the end of the tent building before she rushed over to the shower, telling him to make sure he kept his back to her.

When she yelled out, he almost turned around to see what was wrong before he realized that she was just surprised at how cold the water was.

Beckett showered quickly, scrubbing her skin as fast as possible so she could get out from under the freakishly cold water quicker. She was done within a few minutes and turned off the water, realizing that she had a slight problem now.

There were no towels, or anything for that matter, in the small room they were in so she was dripping wet, and cold.

Shivering, she walked back to her previous place and sat down with her knees to her chest, trying to conserve body heat. It wasn't cold enough for either of them to have a chance of freezing to death, or getting hypothermia, but it was still cold enough for it to be extremely uncomfortable.

A few seconds later she felt Castle sit down just a little ways from her, with his back still turned towards her. Before she could even ask why he was over there, he started answering her.

"The air circulation vent is over there were I was just standing and it's blowing out cold air, and the other side of the room is wet from the shower, this is the only dry and at least slightly warm place."

She was not comfortable with him that close to her while they were both unclothed, but she wasn't cruel enough to make him go back by the vent, or on the wet side, while it was so cold.

They sat in silence, but it only lasted a few minutes before Castle couldn't take it anymore and had to say something.

"How long do you think they will keep us in here?"

"I don't know. I guess until they determine if whatever that stuff was was harmful or not. Which shouldn't take too long, if they are working on it."

"If they are working on it? You think they might not be working on it?"

"This gave them a lead to use to catch this guy and I don't see us being the FBI's priority right now."

"Hmm, you're right. I wouldn't be surprised if Mr. Stuck-up FBI didn't just leave us here for the time being until he caught this guy. Or at least until he exhausts this lead."

Castle continued rambling on about random things, just to break the silence, but she had stopped listening to him, just occasionally letting out an agreeing sound so he would think she was still listening.

While he talked, she got lost in her thoughts, thinking about various things, but mostly about Josh and the man sitting naked behind her.

Josh had been there for her over the summer when Castle wasn't, and though she knew she didn't love him, she was sure that if she had more time, she would have fallen in love with him. And that was the plan, until Castle came barreling back into her life and upset her apple cart again. Before she had arrested him in the fall, she was perfectly happy with Josh, but now that Castle was back in her life, she couldn't help but compare the two of them all the time.

She had done a wonderful job of locking the feelings she had for the writer away in a cage, deep in the back of her mind, and while some of those feelings came back to the surface when he started working with her again, most of them stayed buried.

But little by little they kept coming to the surface and she found herself falling back into their old ways, as if nothing had happened over the summer.

And then her mother's case had come along again, pulling her along for an emotional ride that rattled that cage, but that was nothing compared to the kiss they shared during that case.

That kiss pretty much ripped apart the cage keeping her feelings back and she hadn't been the same since. It only took a day for Josh to notice she was different as well. If asked, he couldn't describe the change in her, but he had gone to the precinct on his lunch break one day, intending to surprise her for lunch, only to witness how she interacted with Castle, and he knew it was the writer that caused this change in her.

She knew that Josh noticed it, which was why she knew he was going to break up with her eventually, but she didn't think he would do it so soon, or at the precinct for that matter. He was a great guy, and they could have been good together. But there was a part of her brain that was constantly nagging at her, telling her that while she and Josh may have been good, she was even better with Castle.

Which left her wondering what the hell she was supposed to do now? As if her mind was trying to answer that question, she suddenly remembered what Lanie had said to her earlier today after she had found out Josh had broken up with her.

"You know what this means, don't you?" Lanie had said when she had cornered Beckett away from the guys for some girl talk.

"No?"

"Girl! Why are you two so blind when it comes to things like this? The ex-wife is gone, and you are single, so what's stopping you two from getting your freak on?" It took her a few seconds to realize that Lanie was talking about Castle, and before she could respond, Esposito was calling her over to show her something about their case so she had waved Lanie off, telling her they would talk later.

But now that she was alone with her thoughts, Lanie's words kept repeating in her head until she was actually considering them. What was stopping them? They were both unattached now, and he was back shadowing her, so he had to still have feelings for her, right? She definitely still had feelings for him.

As much as she hated to admit it, Lanie was right. There wasn't anything stopping them now.

Now she had a choice: Did she want to clue him into her decision, while they were both naked in a quarantine shower, or did she wait until later when they were clothed?

She was weighing the pros and cons of each choice when she finally realized that Castle was calling her name, and if his tone was anything to go by, he had been trying to get her attention for a while.

"What?"

"Finally, geez I was starting to think you had fallen asleep on me back there. Were you even listening to anything I was saying?"

"N-no, not r-really." She replied, slightly stuttering as her teeth started chattering from the cold.

"Cold, Detective? We'd get warm if we were cuddling, you know." Castle said, obviously just teasing her.

"Okay." She replied, obviously going with choice number one.

"W-What?" He said, stuttering not because of the cold, but because his heart and brain had stopped functioning for a second as he tried to process what she said.

"What's the matter, Ricky? It was your idea, now lay down." Beckett watched as he hesitantly did as she said, moving so he was laying down on his side with his back to her. Coming to the conclusion that she was just teasing him, and didn't actually plan to cuddle with him, he decided to tease her back when he felt her eyes on him.

"Enjoying the view of my fantastic backside there, Detective?"

They were back to their normal banter but now that she had come to the conclusion that she had, it felt like the invisible lines they knew not to cross during their banter had been erased. Hours ago, she would have completely denied having been checking out his bare butt, but now?

"Yes. It reminds me of a baby's bottom."

"Thanks...I think? Wait, did Kate Beckett just admit to checking me out?"

"Why is that so shocking?"

"Because-" She took that opportunity to scoot over and lay down next to him, wrapping her arms around his waist and pulling herself flush against him, grinning when his breathe caught.

"Because what, Castle?"

"Because...You...I don't...You... Guh." His mind couldn't function enough to make a coherent sentence, let alone remember what he was about to say when he registered the feeling of her bare breasts squished against the skin of his back.

Beckett couldn't see his face, but she could tell by how tense he was that he was still in shock from her action so she just stayed still, until he finally started to relax against her. Then she started feeling bold.

"You feel pretty cold, maybe I should help warm you up." She started moving her hands across his chest and he squeezed his eyes shut, knowing that as much as he really didn't want to, he had to stop her.

One hand stayed on his chest while the other started traveling down south. Her hand grazed over his stomach, leaving goose bumps in its wake, and instead of going straight down, her hand veered off to the side to dance across his hip bones.

Once she had thoroughly mapped out his hips with her hand, she started to move towards a very important part of him, only to be stopped when he grabbed he wrist.

"I can't do this. I'm sorry, but I can't."

Her mind was racing a mile a minute, trying to figure out what was wrong with this picture, since the last thing he should be doing is stopping her explorations.

He pulled away from her, enough so that they weren't touching anymore, and turned over to face her, his eyes not even attempting to stray away from her face."I don't know what you are trying to accomplish by teasing me like this, but it's cruel to do this to me when you know how bad I want you. I can't take it, so please, don't."

"Lanie said something to me earlier today-"

"So this is the lovely Dr. Parish's idea? Should have known." He interrupted her but she ignored him and just finished what she had started to say.

"-she asked me, now that you and I are both single, what was stopping us from 'getting our freak on', her words not mine, and it got me thinking."

When she stopped talking and averted her eyes, suddenly feeling less bold than she was earlier, he had to encourage her to start talking again.

"Thinking what?"

"That there is nothing stopping us." She nearly whispered to him, suddenly feeling shy now that her decision about their relationship was out in the open.

Despite being a genius writer, it took him a little while for him to wrap his brain around what she was saying. And even then, he wasn't sure if that's really what she meant or not.

"What are you trying to say, Kate?"

She took a deep breathe as she prepared to make a huge leap in their relationship, knowing that things would definitely change between them after this.

"What I'm saying is, is that it's only cruel if I have no intentions of following through." She just smiled at him while he stared at her in shock.

"Seriously?"

"Seriously."

"You aren't just teasing me? You, Kate Beckett, want to be with me?"

"No, I'm not teasing you, and yes, I want to be with you."

He closed his eyes and was silent a for just long enough for her to start feeling uncomfortable, wondering what he was thinking.

"Ashton Kutcher isn't going to pop out of nowhere with video cameras, saying I got Punk'd is he? Because besides the fact that that would be extremely cruel, I'm not exactly comfortable showing this much skin on TV."

"Ugh, Castle, just shut up and kiss me." Beckett rolled her eyes at him and he happily did as he was told, leaning forward to plant a gentle kiss on her lips.

He pulled back a few seconds later, not wanting her to feel like he was trying to rush into anything because the last thing he wanted to do was mess this up, but she followed him and pressed her lips to his in a kiss that quickly turned heated.

Following her lead, he kissed her back just as passionately and soon they were going at it with everything they had. He sucked her bottom lip into his mouth while she grabbed onto his shoulders and pulled him over her as she laid on her back. His mouth opened in a silent gasp as her breasts were pressed against him again, only this time against his chest, and she took that opportunity to slide her tongue into his mouth.

Castle had had a very physical reaction to her when she was pressed against his back earlier, and it had never gone away so when she pulled him on top of her, he figured she would realize what she was doing to him and slow down, so they wouldn't end up taking it too far, but she didn't.

He knew she had to have noticed it, it was kind of hard not to with the way his position half on top of her left his 'reaction' pressing hard against her thigh.

She was doing wonderful things with her mouth, and her hands were back to exploring his upper body, so he figured that she would let him know when they were going too far, and started putting all his attention back onto the feeling of her mouth on his. It didn't take long before he decided to see if she would let him do some exploring of his own and started trailing his mouth down her neck, getting some wonderful moans in response.

Her hands were roaming over every part of him, except the part she really wanted to get her hands on, only because of the way he was laying on her made it impossible for her to reach the hard appendage against her thigh.

Castle made his way down her neck, kissing and sucking every inch of skin along the way until he got a little ways past her collar bone and hesitated, not sure how much further down she'd allow him to go right now.

Sensing his hesitation, Beckett pushed on his shoulder to get him to roll back onto his side and off her, which he quickly did, assuming that was how far she was comfortable with them going right now, but she really only wanted space between them so they could properly explore.

She leaned forward and started kissing him again as he placed his hands on her waist, not knowing where else he could put them, and it only took her a minute to realize why he wasn't moving them.

"Castle?" She said breathlessly, and he knew right then that he would never hear a sexier sound than his name coming from her like that.

"Yeah?"

"Stop hesitating and touch me like I know you want to."

"I'm not sure how far you are comfortable with me going though." He said honestly and she smiled at him.

"I'll tell you if you go to far, okay?" He nodded his head and instantly his hands were sliding up and down her sides, committing every inch of her to memory, wondering when he would finally get to explore all of her.

She brought her hands up to fist in his hair while she devoured his mouth again, enjoying the feel of his hands running all along her body.

He still wasn't touching the places she wanted him to though, so she decided it was time to take matters into her own hands. Literally.

Castle sucked in a sharp breath when he felt the first brush of her hand against his hard length, trying to convince himself it was just an accidental touch when she did it again, this time brushing down the entire, impressive, length of him.

"Kate?" He managed to choke out, but she just shushed him and continued stroking him, trying out different strokes to see which ones he seemed to like the best. Figuring that if she was touching him like that, he could probably get away with being a little bolder so he trailed his hands up from where they had been resting on her butt, all the way up to her chest.

She moaned at the first touch of his hands on her breasts, but didn't tell him to stop so he started playing with them, squeezing gently and rolling her now hard nipples in between his fingers.

He was just about to lean down and take one in his mouth when there was a noise outside the plastic building they were in, causing them to spring apart and look at the door.

A few minutes passed in silence before they figured out that no one was coming for them yet and Beckett turned her head to see Castle staring at her.

"See something you like there, Castle?" He snapped out of his daze and grinned at her before standing up and walking over to where she had landed when they had jumped apart, watching as her eyes drifted down south when he got closer to her.

"As a matter of fact, I do." He sat down next to her then gestured for her to come closer, when she did he grabbed her arm and pulled her so she was straddling his legs, facing him.

She sat there as he stared at her, trying not to feel self-conscious about his intense stare as he was finally able to get a really good look at her body, since before they were so close together that they couldn't really see much in the dim light of the building they were in.

Seeing that he was making her uncomfortable, he leaned forward for a kiss, and after she responded to his kiss, started trailing down her neck again. This time he didn't stop below her collar bone, he kept going until he was gently teasing a nipple with his lips and teeth, grinning as she started moaning and rocking her hips against his leg.

He spent an equal amount of time pleasuring each breast and by the time he released the second nipple from his mouth, she was craving more.

Knowing he wouldn't go that far on his own, she took one of his hands and placed it between her legs, rubbing against his hand and making it clear what she wanted him to do.

Once she had his hand where she wanted it, she had intended to get back to her task of playing with his hard member, but she didn't account for his extremely talented hands that had her close to the edge within just a few minutes, leaving her unable to focus on anything else but his hand.

Castle watched in fascination as she came apart on his hand, collapsing against his chest as the aftershocks of her orgasm traveled through her.

When her breathing went back to normal, she lifted her head of his chest and met his lips for a duel of tongues while she removed her legs from him and slowly guided them down until he was laying on top of her again, only this time she made sure he was directly on top of her. He was so busy kissing her that he hadn't even realized what position they were in until he felt one of her hands reach down and grasp him, positioning him where she wanted him to be.

"Kate, god Kate, we can't do this."

Having completely expected this question she just smiled at him and shifted her hips to rub against him, making him groan.

"Why not?"

"Because...Because it's too soon. I don't, I don't want to screw this up, don't you think we are taking things a little too fast."

"Not really, not for us." She was shifting against him in a steady motion, not taking him inside her just yet, making it hard for him to think straight.

"But... They didn't even give us clothes, I hardly doubt they were kind enough to leave a box of condoms lying around."

"I'm on the pill, are you done now?"

"Yes."

"Good." She hooked one of her long legs behind his back, and in one smooth motion, took him inside her, causing them to both groan at the sensation. They stayed still for a moment, letting Beckett adjust to him before he finally started moving, drawing a moan from them both.

She wrapped her other leg around his back and locked her heels together and he took that as a sign that he could move and started up a slow, but steady rhythm. It didn't take long for him to find the angles she liked best, and he continuously entered her at those angles, trying to bring her over the edge quickly because he knew that he wasn't going to last very long himself.

As he felt her inner muscles start to clench around him, he leaned over her and captured her mouth with his before he thrust in deep and rubbed her clit with his free hand, causing her to cum which triggered his own release.

Completely satisfied with the fact that he had just, finally, had sex with Kate Beckett, he wrapped his arms around her back and pulled her body with his as he rolled onto his back so she was lying on top of him, not ready to pull out of her and break that connection just yet.

Beckett laid their for a while, content to just relax while Castle threaded his fingers through her hair, but she knew they needed to get up before the hazmat guys decided to finally let them out.

After much complaining on Castle's part, he could care less if they found him spread out on the floor and didn't see why he had to get up too, they cleaned up a little bit in the shower then settled down with Castle sitting with his back against the wall, with his legs spread, and Beckett sitting between them with her back against his chest and his arms draped across her stomach.

An hour later, the powder was deemed harmless, the only thing it does is knock you unconscious for a little while if inhaled, and Castle and Beckett were released from the quarantine after the FBI agent finally realized he wasn't going to be able to solve this case without them.

So this was supposed to be short, or at least a decent length...Not really sure what happened to turn it into this huge thing...

Aren't hazmat suits usually white? Why are they orange in the promo pics? I just now noticed that and I could change them to orange in the fic, but it's odd so I'm leaving them white.