Disclaimer: The only part of Castle that I own is the TV on which I watch the show.

It all started at Hallowe'en, quite by chance, and it has been haunting her for months. Not haunting, more like plaguing. Irritating. Ticking off. But lately? She admits this to no one but herself: arousing. Arousing to the point of her occasionally having to absent herself in the middle of theory building and go calm down in the ladies room.

During the vampire-werewolf murder investigation last October, Castle had been lolling in a chair, going over some photos, and she'd stepped behind him to look at them.

"You smell like cherries," he'd said.

When she'd whipped her head around to glare at him she'd found that they were only inches apart. His face must have been almost buried in her hair. Her hair that she'd used brand-new cherry conditioner on that very morning.

It had been disconcerting. No, it had been electrifying. But she'd turned that switch off then and there. Not having that. Nope. Absolutely not. She'd turned off the switch, but she hadn't counted on the static electricity.

A few days later–all right, all right, she knows exactly what day it was: November fifth. Guy Fawkes Day. They'd been in the car on a useless stakeout and Castle had been yammering on about Guy Fawkes and gunpowder and its "noble and ignoble history." That had led to him to think–and talk incessantly–about having Nikki Heat foil a gunpowder plot but a minor diversionary explosion blows her clothes off and the gentlemanly Rook covers her up with his jacket. "Kind of like Sir Walter Raleigh putting his coat over a puddle for Queen Elizabeth," Castle had said.

"Except that Queen Elizabeth was fully clothed."

"I didn't say it was exactly the same, Beckett."

"If Nikki's clothes get blown off, why don't Rook's?"

"They're sturdier. Heavier fabrics, more buttons and zippers to keep them on."

She'd snorted. "You just don't like writing about yourself naked."

"Me? I'm not writing about me, I'm writing about Rook."

"That's what I meant."

"Not what you said, though. You angling to get me naked?"

"Oh, please." Well, yes, oh please, now that she allows herself to think about it. Because during this conversation he had leaned over to refill her coffee from the Thermos that he'd brought and she was suddenly aware of his intoxicating grapefruit-scented aftershave. She'd been sure that he'd never worn it before. It had done weird things to her, like make her want to grab his deliciously citrusy face and kiss it for a very long time. And what was really astonishing? Five months later when a bomb destroyed her apartment and nearly killed her, Castle really had been like Sir Walter Raleigh. She doesn't know if he'd forgotten their stakeout conversation or just hadn't wanted to bring it up. It must have been the latter because Castle not only has an elephantine memory but loves coincidences more than anyone she knows. She'd been naked in the tub and he'd covered her up with his jacket and lead her out of the burning apartment. Sir Walter–Richard– Castle.

That was three weeks ago. She's in her new, incendiary-free apartment right now, soaking in the tub, surrounded by fragrant bubbles. What she's noticed about Castle since his cherries comment is how good he smells. Astonishingly, overwhelmingly good. Even if they've been crawling in some dumpster looking for evidence, or on the job for 24 hours straight with no way to wash their hands, or stuck in interrogation with someone drenched in booze or vomit or both, he smells fantastic. She has been surprised to realize that he has no signature scent; he must have a panoply of aftershave and hair products. Oh, God, she's even beginning to sound like him. Panoply? That's the kind of word he'd use, instead of something like "array" or "shelf." He's beginning to infiltrate her brain, or at least the part of it that governs word choice. She uses her toes to turn on the faucet and up the bathwater temperature a little, even though she knows that she's quite hot enough just thinking of Castle.

She's just finished reading Marshall McLuhan on the five senses, and drops the printout that she'd made onto the tile floor, where the slightly soggy article lands with a splat next to the bathmat. McCluhan maintained that sight is the most important of the senses, and ranked smell a lowly fourth. (Taste was at the bottom of his rating scale. She bets Castle would disagree.) She's no Marshall McLuhan, but she's a hell of a detective, if she does say so, and she wishes that she could argue with him about the importance of smell. At the moment, anyway, she's inclined to put it at the top of the list. She possesses one of the most important attributes of a good detective: a nose. A nose that can sniff out a lie; a nose that can sniff out bullshit; a nose that can sniff out danger, worry, discomfort, excitement. A nose that with increasing frequency buzzes her brain whenever Castle–or the scent of Castle–is nearby. And that's the problem. When she was in the break room last Wednesday she smelled sandalwood at least three seconds before he stepped through the door, and apparently looked so swoony that he asked her if she felt all right. This morning while getting ready for work she had caught herself mentally cataloguing his scents and trying to decide what he'd be emanating today.

There goes her timer. She quickly gets out of the tub, dries off, puts on a pair of sleep shorts and a camisole, and pads barefoot into her bedroom. It's a little warm for the middle of April, and she tosses the duvet aside as she gets into bed and turns on the television. Bobby Mann is a jerk, though marginally more tolerable than his loathsome sidekick, Hank McPhee. She's tuning in to the show only because Castle is a guest. Oh, shit, there's that nitwit starlet Ellie Monroe. One more "like" out of her and the mute button will be deployed. Three, two, one, there it is. She picks up the remote, silences the actress and mutters, "I don't, like, like you, Ellie."

Within moments she loathes her, and she's seriously pissed at Castle.

"Wow, like I can't believe I'm meeting you right now." That's what Ellie Monroe says when Castle arrives on set, already making goo-goo eyes at him.

"Really?" he says, all fake modesty.

"Well, you're, like my favorite author ever. I mean, I've read Heat Wave at least three times." Really? And he falls for that? The woman probably can't even read without moving her lips.

By the time she oozes, "I didn't know you worked with law enforcement. It's kind of my weak spot," and he oozes back, "Call me old-fashioned, but when a beautiful movie star is impressed with fake law-enforcement credentials, I'm in," Beckett is ready to hurl both her dinner and the nearest available shoe.

As she goes to sleep, she wonders what cologne/aftershave he'd been wearing this evening, as Ellie Monroe all but draped herself over him, but comforts herself with the thought that at least that's the end of it. She won't have to see or hear about Ellie Monroe again.

Wrong, dead wrong, she mutters to herself the next day. It's not the end of it–except for Bobby Mann, who had been poisoned shortly after the show and is face up on a slab in the morgue. She and Castle stand next to each other, and as they look at his body her mind, directed by her nose, keeps wandering. Even surrounded by the smells of the autopsy room she can detect something delicious and summery on Castle. She wants to bury her nose in the dip between his clavicle, but she can't. What is it? Aha! Blackberry. It's blackberry. She could eat him right there. Not that kind of eating. Okay, that kind. She blushes as she turns to leave.

"You okay, Beckett?" he asks as they walk shoulder to shoulder down the long narrow corridor.

"What?"

"You made a funny sound."

"I never make a funny sound."

"Au contraire."

"Since when do you speak French, Castle?" She looks sideways at him. He seems a little smug.

"My French is mostly limited to food, granted, but I can toss out the odd appropriate phrase."

"Yeah, well. I didn't make a sound, funny or otherwise."

"Did, too. Plus now you're sniffing."

"What?"

"Sniffing."

"I am?" Oh, God, she had been. It's the damn blackberry he has splashed on. Away from the autopsy room the smell is even better. "Must have a cold coming on."

He gives her a look and squints one eye. He knows she's fibbing. She hopes that that's the low point of the day.

It isn't.

They spend all afternoon tracking down leads and interviewing a number of people, including two of the vic's six ex-wives, and begin to make some headway. But while they're going over the case in the bullpen, Castle's phone rings. Ellie Monroe. She wants to get together with him this evening. Castle says that since they were Bobby Mann's last guests "it would be comforting if we were together." And off he goes, practically drooling and trailing pheromones behind him.

"I hate you," she whispers as she watches the elevator doors close on her partner. "But I hate her a thousand times more."

It's a lie. Half a lie, anyway. She definitely doesn't hate Castle. Au contraire, to quote him. When she gets home she drowns her sorrows in two glasses of wine, two cups of coffee, and the remains of a bag of stale peanut brittle that's one of the few things that survived the explosion in her previous apartment. She doesn't want to think what he and Ellie Monroe are eating. Or who.

She doesn't want to think about it, but she does have to face it the next morning when Castle saunters into the precinct and says "Good morning" with a look-at-me tone.

Irritated, she snaps, "Lose the 'I just got laid' voice, all right?"

"What are you talking about?"

Oh, she hates that fake innocence. Wants to smack it right off his face. Which, by the way, she does not like the smell of. Not one bit. "I'm a trained detective, so don't bother denying it."

"Okay, fine."

Her irritation meter registers even higher. "Oh, so now you're not denying it?"

"You just told me not to."

She's seldom been so grateful to see Ryan and Espo walk by her desk, so she can ask them if they have any news. Whatever it is it will help her control her flaring nostrils, which are reacting to the distinct aroma of sex and a woman's perfume that Castle is radiating. Obviously Ellie Monroe's perfume. Not top-of-the-line, by the way. Nowhere near. She's itching to say that to him, but discretion holds her back. When his phone rings a minute later and a photo of him and Ellie pops us, though, she regrets not having said anything. Castle met the woman less than three days ago, slept with her the next night, and the so-called actress is already on his freaking phone with her own freaking love song ring tone? What an ass he is. What an ass she is to have thought that he'd grown up and ditched the playboy crap. When Castle makes a date to see Ellie again this evening, Beckett almost gags.

The case develops in an interesting way, and Castle–loath as she is to acknowledge it at the moment–has some great and productive ideas. Except that evening when she and the boys want to ask him something he is, of course, out with Ellie. Maybe it's unfair of her to expect him to stick around when he's not paid to hang around. But goddammit, he should hang around when they're working on a case, instead of hanging around with Ellie Monroe. Although hanging around is assuredly not what the lovebirds are doing.

She calls it a night, and sends the boys home. She doesn't want to go to her empty apartment, so instead she remains at her desk doing busy work. Busy work like what was that crappy perfume that was still clinging to Castle this morning? She has good olfactory recall–hey, there's a term Castle might like, if he were here sitting opposite her instead of doing whatever he's doing with the D-minus actress awash in C-minus perfume–and wonders if she can isolate his various scents. Make a list. Just for her own amusement. Enlightenment. Make a game of it. Nothing wrong with that. It's really an excellent exercise for a crime fighter. Like that sandalwood stuff he was wearing the other day. What were the grace notes, the little touches that complemented the sandalwood so well? There was a trace of something lemony that wasn't lemony. Grassy. Woodsy. What was that? She does a little Google search. Vetiver! That's it. She pokes around a little more and congratulates herself when she's sure that she's found the cologne in question. Seven hundred dollars a bottle. English. Sounds like Castle. So vain. Maybe she'll drop the name of it into the conversation some time, see what he says. If he's around for a conversation and not busy leaving his seven-hundred-dollar scent all over the starlette's sheets. She's proud of coining a new word. Starlette: an actress who's one pigeonhole beneath starlet.

So she's jealous. So what? She can't help it. He should be here. She takes her bag out of her drawer, which she then slams shut, and stomps to the elevator. There's a cab coming her way and she hails it. No odoriferous subway for her tonight, though it would probably smell better than that C-minus perfume.

Sure enough, next morning, here he is, strolling into the precinct long after she gets there. There's a wolfish aura about him, and it's nauseating. Almost as nauseating as the sex-and-perfume smell that he's sporting again. She shouldn't let it get under her skin. Trouble is, he's under her skin now, and she wants him to stay there. What she really wants is him to be on her skin, for them to be skin-to-skin, mixing scents.

He's only just settled in when his phone rings, and she prepares to grit her teeth. But it's not Ellie. It's worse: it's the producer of the Nikki Heat movie, whom Castle has apparently convinced to hire Ellie for the title role. This time she can't keep quiet, but when she says to Castle that Ellie had thrown herself at him so that he'd recommend her for the movie, he's indignant.

"You just can't stand it that a beautiful actress is actually interested in me."

"Why would I care?"

"Exactly. That's a good question. Why would you care?"

"I don't."

Oh, but she does. And before she can dig herself into a bigger, nastier hole, Esposito shows up with some important information and she turns back into the professional whom she had briefly and embarrassingly abandoned. To his credit, so does Castle. They pursue the case deep into the evening, and neither one of them has time to address the scantily-clad elephant in the room. Exhausted, she goes to bed as soon as she gets home. She's sure that he does, too, the difference being that she's alone and he's not and has undoubtedly found all the energy he needs.

When he comes to work the next day he's not as cocky as he had been. When she asks how his date was, he asks her how she knew he'd had one. She plucks a brunette hair off his jacket and explains, yet again, that she's a trained detective. Castle complains that the date hadn't gone well, and puts the blame on her. "You made me doubt Ellie's honesty. Foolishly, I told her what you said. Made her cry."

She's not taking this lying down, or standing up. "Castle, she's an actress. A professional liar. She's paid to cry on cue."

Before the conversation can get even worse, they're thrust back into the investigation. Several hours later they think they've got a break–a tape of Bobby Mann's producer apparently making threats on the talk show host's life–until he provides a provable alibi for the relevant time frame. He'd been in bed with an actress who wanted a role in his new sitcom. The actress? One Ellie Monroe. They bring her into the precinct and she happily admits it. And just like that, Beckett's annoyance with Castle turns into something else: regret. He's been had, and she feels sorry. And in one secret place in her mind she exults, because the starlette is out of the picture–every picture, but the most important the personal one.

He looks rueful. "Well, go on, you can say it. 'I told you so'."

"No thanks. I'm actually not in a gloating mood. His alibi sets up back to square one."

She's sure that he's hurt, but he puts on a good, jokey face, and says that the good news is that now his evening is free. And then he adds, "I think I know who killed him." Turns out he's right: the murderer is Bobby Mann's reprehensible, longtime sidekick, Hank McPhee. They have little trouble getting his confession, and she afterwards she takes the plunge and invites Castle out for a burger. When he says no, that he has a date, fury floods her.

"You're going out with Ellie Monroe even though you know the only reason that she was interested in you was for a part? Have you lost all sense of human decency and self-res... What?"

"My big date is with Alexis. She's getting back from her trip."

She's both chagrined and elated, but lets the former go, holds on to the latter, and sincerely wishes him a wonderful evening. She feels elation building and hope blooming, and stays at her desk for a bit until she tells herself, "It's time." When she retrieves her bag she's smiling, and shuts the drawer gently. Looking around the bullpen and ensuring that it's empty, she does a little dance before calling for the elevator. "Going down and going up," she says happily.

On her way home she makes two quick but important shopping stops. Nervous to the point of nausea but aware that she should eat something, she has a stomach-soothing poached egg on a piece of toast. After that it's a soak in the tub with the new way-out-of-her-price-range bath oil that she just bought. It will, please Lord, be worth it, as will the equally budget-busting lingerie that was the object of her second shopping stop.

For the umpteenth time, she checks the time on her phone. When it hits 11:00, she texts him, figuring that his daughter is asleep.

"Alexis have a good time?"

He must have the phone in his hand because his answer is instant. "Great time, thanks."

"It's late, but if she's in bed is there any chance you can come over?"

The second response is not as fast in arriving. "Come over? You mean to your apartment?"

"Yeah. There's a big break in a case and I'd like to talk to you about it."

"What case?"

"One from last year. Don't want to discuss it here."

"On my way."

Knowing Castle–and she does, though not as intimately as she hopes she soon will–she figures she has no more than fifteen minutes to wait.

Nine.

"Geez, Castle, that was fast," she says, opening the door

"Paid the cabby a hundred bucks."

"Wow."

His expression changes from open and friendly to surprise and ill-concealed pleasure. "Uh, no, the wow is on me. You look unbeli–. You. You, um." He's bumbling. "Those aren't your work clothes."

Damn right they're not. She's barefoot and dressed in flowing silk pants and a fitted, very sheer blouse through which even someone with terrible vision–and his is 20/20–could see her new, wildly expensive lace-trimmed bra. "Your detective skills improve every day, Castle. Come on in." She's pleased that he's trying but failing to keep his eyes above her neck. "Want to hang up your jacket? It's kind of warm in here." And getting warmer.

"Oh. Right. Sure. Jacket off." He needs three tries to hang it on a hook. She sees him swallow hard and flex his fingers. "So, big break in a secret case? I'm all ears."

Not all ears. His newly flushed cheeks are evidence of that.

She's put a bottle of wine, which she opened half an hour ago, and two glasses on the coffee table. "Want to sit down? Have something to drink?"

"Drink?"

"Yeah, drink. You know. I have a nice bottle of red for us."

He perches nervously on the sofa, and when she pours the Malbec she sees him wipe his presumably sweaty palms on his Levi's. "Cheers," she says, touching the rim of her glass to his and deciding to let him make the next conversational move.

"Thanks, Beckett. I can't. I, er. I'm trying to think what case this could be." He takes a sip. "Nice."

"What case?"

"Yeah."

"Ours."

"Oh." That takes him aback. "Ours? I figured it was ours. We've had a lot of cases. Last year. A lot, right?"

"Our case." she says, setting down her glass and moving slightly so that her right leg is only inches from his left. "Ours as in us."

"Us?" He sounds as if he's strangling.

She inches a little closer. She's not going to take a long time to get to the point. She's already taken way too long, even though she feels as if she's acting uncharacteristically impetuous. And if she doesn't act quickly she'll lose her nerve.

"You remember that vampire-werewolf case last year?"

He relaxes in what looks like blissful relief. "Oh, yeah. I loved that one."

"You remember telling me then 'You smell like cherries'?"

Visible tension returns, maybe something like panic. "Oh. Yes. Yes, I do. I'm sorry. That was inappropriate. Right? I shouldn't have said that."

She leans sideways, turns her head until her nose is a millimeter away from the soft spot under his left ear, and inhales. "You smell like bitter orange. I'm always surprised that something called bitter is so sweet."

He's silent, an unnatural state for him. His blue eyes widen. And then she puts her hand on his thigh and his muscles twitch. It makes her shiver.

"I thought I minded that you said I smelled like cherries. Overstepping the boundaries, you know? But it actually kind of thrilled me. I didn't know what to do with that, so I shoved it to the back of my mind, some almost inaccessible place. But it turns out that I kept going back there. And what happened was that I kept noticing how incredibly good you smell."

"You did? I do?"

"Yeah. Keeps me up nights sometimes, trying to figure out what your aftershave or cologne or soap or hand cream or hair product is."

"I keep you up a night?" He sounds like a boy soprano, which he decidedly is not.

"Lately? A lot. Especially this week. Because of Ellie Monroe."

"Oh." Now he looks deflated.

"You know why?" She was going to wait for an answer, but she changes her mind. "I was mad at you."

"Mad at me? What did I do?"

"You had sex with her."

"Well, she wasn't a suspect." He puts his hands up. "Okay, okay, you were right that she was using me. But I had a good time."

"You could be having a good time with me. I wasn't just mad, I was jealous."

"I–"

"You're gonna have to let me finish, Castle, while I have the guts."

"Guts. Okay."

"See, understanding my jealousy was the big break in the case I'm talking about. The case I have on you, and I'm pretty sure–oh, God, I'd better be right or I'm the biggest idiot on the planet–that you have a case on me, too. I fought it for such a long time, but I'm out of fight. Although if it had come to it I might have had a cat fight in an alley with Ellie. You'd have loved that, wouldn't you?"

He coughs so hard she wonders if she should get him some water, but he recovers. "My money would have been on you."

"I should hope so." They're thigh-to-blistering thigh now. "See, you came to the precinct smelling of her, and I wanted you to smell of me."

"You smell like jasmine," he blurts.

She smiles. "I do. Bath oil. Bought it on the way home." She takes a deep breath, because this is it. "Jasmine and bitter orange. I think they'd be incredible together, don't you? Like us. I think we could be incredible together." She moves into his lap, her legs bracketing his. "Sorry I waited so long to say that, but I had to be sure of myself. I'm going to stop talking now." She takes his face in her hands and begins to kiss him, very slowly, very softly, and when she adds some pressure and then some tongue his response is fast and anything but soft. He kisses her like a man possessed, and one who wants to possess her. It's the best kiss of her life. She feels him hardening against her, and with what functioning wits she has she starts unbuttoning his shirt. He follows by unbuttoning hers, but never takes his eyes off her face. His hands, the flesh incredibly silky, move around her rib cage and he undoes her bra, slipping it off her shoulders.

"Is that all right?" he asks, dropping it to the floor where their tops already lie.

"No."

"No?" He startles and withdraws his hands as if they'd been scorched. "I'm sorry, I'm sorry, I thought–"

"Shh. I meant it's not all right to stop there."

His eyes are no longer glued to her face. "Your breasts are. Are." He gulps.

Oh, shit. "Small, I know."

"No. Perfect, I was going to say perfect. They're perfect. You're perfect." And with that he captures one breast in his hot, wet, mouth and the other in his hand.

She's a goner, rocking hard against him, and leaves her exploration of his chest just long enough to speak. "Know what we're doing, Castle?"

He unlatches his mouth. "God, I hope so."

"We're making scents. Get it? Scents, with a T."

"Makes sense to me, Kate."

"Know what else makes sense?"

"What?"

"That you take me to bed. Right now. Before we both explode."

In one quick move he gets to his feet and pulls her legs around his waist. "I dunno, Beckett. I think I'd like to explode with you."

"I was thinking more like in me, which is where I want you."

"Oh, I love it. You're going to talk dirty."

"You have no idea."

"Probably not, but I've been waiting."

"You have, huh?" He's dropping her on the bed. "How long?"

"Since you told me I had no idea. March ninth of last year."

She grabs the waistband of his jeans and pulls him on top of her. "Okay, then. You want to know something else?"

"From you?" He's grinning, and pushing the hair off her forehead. "Of course."

"I love the way you smell. But now I want to find out how you taste."

A/N From a prompt by mobazan27, though I set my story before they were together: "Maybe he comes home from a meeting smelling like other women and she wants him smelling like her." Happy new year, everyone. Your company here definitely improved the horrors of 2017. Now I will get back to my story "Well, That's a First."