Warning: Possible minor spoilers for 4x15 and 4x16. If you've seen the promos, you're probably okay. Maybe small stuff from a couple of the sneak peeks, but I really don't think it's anything that wasn't in the promos. All speculation and what I'd like to see happen, of course.

"You had our car bugged?"

Furious. That's the only word that comes even close to describing the look on her face when she catches sight of herself in the dark-tinted window. Absolutely furious.

"Detective, you have to understand..."

Beckett whirls so quickly that the other woman visibly flinches, and she feels a brief surge of satisfaction at managing to at least somewhat unnerve the beautiful, intimidating woman that once served as the inspiration for Clara Strike.

Sophia Turner takes a step back, one hand palm out in front of her.

"CIA, remember?" she says, but there's no smirk, no real hint of superiority, just a fact stated.

Which somehow makes things worse. Because Kate can see how he must have fallen for her. She's not only gorgeous (her hair is perfect and she's got curves the detective has always wished for and a bright smile that any man would fall over himself to see) and smart (she must be, to be running this particular op) but she seems nice as well, truly kind. And obviously she and Castle had gotten along well. At least, the detective hadn't noticed any hint of bad blood between them.

"Detective Beckett, can I call you Kate?" the other woman asks, but she receives her answer in the form of a fiery glare. "Detective Beckett it is, then."

Kate sinks into one of the chairs at the small table in a room whose purpose she has not yet determined. She knows she was supposedly brought here to be debriefed after the events of the past few days.

Castle was taken to a different room. Where, she doesn't know, but at least it was with a male agent and not this woman whose exact role in her partner's life is still firmly in the realm of conjecture.

Thank goodness for small favors.

"Detective," the agent tries again. "There was never anything between Rick and me. Nothing romantic, I mean."

The detective looks up at that.

"Aren't you supposed to be debriefing me?"

The other woman sighs and runs her fingers through her hair.

"Fine. Don't speak a word of this. It's a risk to national security. Basically, pretend none of the past few days ever happened. Consider yourself debriefed. Happy now?"

Beckett nods, and moves to stand, but the agent has more to say.

"So you weren't the first person he shadowed. Don't read anything into it beyond that he's a good writer who believes in researching his books as fully as possible."

The detective turns narrowed eyes back to the woman across the table, venom lacing her words.

"Exactly how many of our conversations did you hear?"

Turner shrugs.

"Enough," she answers. "Enough to know that I needed to head you off."

Kate leans forward, both elbows on the metal tabletop.

"Head me off? What is that supposed to mean?"

The agent slides into the seat across from the detective, watches her for a moment. Kate feels as if she's being studied - weighed, measured, and perhaps found wanting. She's not entirely certain what the other woman thinks of her.

"We met, of all places, in a grocery store," Turner says with a chuckle. "I'd just finished reading When It Comes to Slaughter, and I recognized him from his picture on the back. There he was, an already semi-famous author, with a jar of baby food in either hand and a mystified expression on his face."

Kate represses a smile at the image of the broad-shouldered man, much younger then (cute, Beckett had called him once), carefully examining the two jars with no small measure of confusion in his bright blue eyes.

"He didn't have on a wedding ring, and he didn't look old enough to have a kid," the woman continues. "So I thought maybe he was going to use the baby food for some kind of weird murder research. I mean...angry Wiccans, meat hooks, vampire bikers - he didn't exactly seem to lack imagination when it came to killing off characters."

She's right of course. Some of Castle's earlier books did verge on the bizarre. Kate remembers the first time she read some of the scenes, wondering how any normal human being could have come up with these things. Of course, her partner isn't exactly normal, is he?

"So I sidled up next to him, and I flirted," the CIA agent confesses, a hint of a smile that Kate doesn't like playing across her lips. "He immediately asked me if he should buy Apples & Chicken or Sweet Potato & Turkey for his baby girl. He said he'd gotten out of the shower to find his wife in tears over the fact that they'd somehow run out of baby food, so he'd dashed out to pick up a few things. He pulled up the leg of his very wrinkled jeans. He hadn't put on socks, he said, or even his watch or ring. He just ran."

The detective chuckles.

"Not what you expected then?"

Sophia - and maybe it's okay now to call the woman by her first name, though she won't do it out loud quite yet - shakes her head.

"Not at all what I expected," she confirms. "But my sister's daughter had just passed that age, so I confidently recommended that he avoid the Apples & Chicken unless he wanted to experience particularly interesting spit-up."

Kate really does laugh at that, a little of the heavy tension in her chest easing at the look she can picture him wearing - mixed disgust and fascination, combined with the tenderness she sees anytime he even thinks of his daughter.

"He thanked me for my help, and we went our separate ways, only to end up in the same line for the cashier," the agent says. "I told him I'd read a couple of his books, on the rare occasion that I had free time, and he asked me what I did for a living."

The detective smirks.

"I can just imagine his reaction when you told him," she says slowly.

Turner nods, a half-smile quirking her mouth, eyes glazing a little, perhaps in memory.

"He was thrilled. Said he'd been calling an old college friend of his who he thought had joined the Agency, but hadn't heard anything back from the guy. He asked if I'd mind meeting with him sometime in the next few weeks, answering a few of his questions. As long as it didn't compromise national security of course."

Kate nods. He'd been a little more suave in her case, a little quicker to use his connections to get his way. But she's glimpsed his eager excitement enough times that she can easily imagine his reaction to finding out that the woman who helped him pick out baby food in the grocery store works for the CIA.

"And so Clara Strike was born," she says dryly. "Derrick Storm's handler."

The agents shrugs, spreads her fingers on the table between them.

"He'd call and leave me messages sometimes, needing insight for a particular scene. I'd call him back at the end of the day and tell him what I would do, how I would handle the situation, and then there would be nothing but furious typing on the other end of the line. I hung up the first time, but he called me right back. Eventually, I learned to just leave it connected and go about my business, eating supper or doing laundry or watching something on tv."

Something stirs in Kate's stomach, a twisted feeling at the thought of the other woman staying on the phone with him for long minutes, maybe an hour or more as the author wrote. He'd done that with her once, maybe twice in the very beginning, before she threatened to shoot him if he didn't let her be.

"He told me he wanted to see how it was for a female agent in the CIA, so a few times, I let him come into the office with me. Never on the field work of course, just the less dangerous aspects."

There's no judgment in the other woman's voice or expression, but Kate can't help feeling guilty anyway. Yes, he coerced his way into her cases, into following her in the field. But recently - for quite a while, actually - she's wanted him there at her side or just behind her. And even with his WRITER vest, she knows he's far too vulnerable. They've been lucky, so unbelievably lucky that nothing has happened to him aside from mild hypothermia and some bruised knuckles.

"He was fun to have around in the office," Turner says. "Made things a little more interesting. We have slow days here too, when it feels like we've got nothing, but he'd sit there and spout of these crazy theories about aliens and-"

"-and CIA conspiracies," Kate says without thinking, blushing when she she sees the agent's grin. "Sorry, I didn't mean to..."

Turner waves it off, leaning forward with her elbows on the table as if she's sharing some deep, dark secret.

"I really should apologize for him subjecting you to those, since I'm sure it's at least partially my fault," she says quietly, smiling at the confusion Kate knows is etched across her own face. "I liked to mess with him, you know, make up stories about shadowy figures and all that. But I don't think he realized that nine times out of ten, I was feeding him complete fabrication."

The detective feels herself warming to this woman, and if it weren't for the something still niggling at the back of her brain, she think they could be friends.

"So he spent all this time with you..." she says, leaving the statement open for interpretation.

Turner studies her for a moment, then shakes her head.

"I had a huge crush on him for awhile," she finally admits. "I mean, how could I not? He's smart, good-looking, funny, kind. Any woman would fall at least a little in love with him."

The detective's heart clenches in hurt, and it's all she can do not to push away from the table and walk straight out.

"But he was married," Turner reminds her. "And Rick Castle doesn't cheat. Besides, I never would have wanted him that way if he did."

The woman shakes her head, one hand lifting briefly from the table, curling into a fist.

"He came onto me exactly once."

Kate listens, can't make herself stop for some reason, despite the fact that she doesn't want to hear about whatever this was between them.

"He'd been MIA for a couple weeks," Turner says. "No phone calls, no messages, no showing up at the office without warning. I was worried, so I finally tracked him down at his apartment. When he answered the door, he was holding a crying Alexis and he looked like he hadn't slept in days. He told me he'd caught Meredith sleeping with her director and she'd left. He'd just gotten the divorce papers."

The woman looks up at the artificial lights, an odd grimace on her face before she schools her features and continues.

"I reached out and Alexis came to me, despite the fact that I'd only ever met her once. I calmed her down and got her fed and settled for a nap. Then I sent Rick off to take a shower and a nap himself and I cleaned up the apartment and cooked them my mom's chicken noodle soup."

There's something utterly heart-breaking about the mental image of her partner in that state, and amid her own doubts, Kate needs to know what happened. She gestures for the woman to go on.

"When he woke up, he nearly cried when he saw what I'd done. He told me that Meredith had been cheating on him for ages, and all the while I'd been his friend and I'd been there for him, and then he kissed me."

A sharp jealousy flares up in the detective's gut, and she starts to turn away, but Turner catches her by the hand.

"Beckett, wait," she says quietly. "Just listen."

Kate stills and faces the woman once more.

"I didn't kiss him back. I hugged him. I told him I was so sorry for what he was going through and that I'd help however I could. But I wouldn't be the rebound girl. I wouldn't let him ruin our friendship that way. And he got it."

Kate knew. She knew first-hand how he'd back off if he thought he wasn't wanted. She knew he'd respect the wishes of any woman, especially one he considered a friend or more.

"He started dating someone else not long after that, and I did too. Married him eventually. We just celebrated ten years."

The detective glances down at the woman's empty left hand and finds amusement in her face when she looks back up.

"We went to the Bahamas for our anniversary, and I lost it snorkeling. Haven't had a chance to replace it yet."

Kate nods and opens her mouth, but the other woman speaks first.

"I still read his books, you know," Sophia confides. "And what he said the other day in the car? He's right: Nikki Heat really is a more complex and nuanced character than Clara ever was."

The detective is torn between the feeling of violation at knowing someone was listening to private conversations between her and her partner and the blooming sense of pride in her alter-ego and what it reflects on how Castle sees her. Still, she has to know for sure. Has to be absolutely certain.

"And those sex scenes between Storm and Strike?" Kate asks quietly.

The agent chuckles.

"You should know by now just how vivid his imagination can be. Personally, though, I think the ones in the Heat series are far more...interesting."

"So you never..."

Sophia shakes her head.

"No, we never." she says. "And you? That strip Proust scene in Heat Rises was something else."

Beckett leans back in the chair, horrified both at the question and at the sudden fluttering in her chest and lower regions.

"What? No! We haven't...I mean, we're not even together yet!"

The agent raises an eyebrow, and Kate realizes exactly what she just said.

"Yet?" Turner asks with a slight smirk.

Just at that moment, a knock sounds, and the detective turns, sees that the door to the office wasn't completely shut. It swings open fully, and there stands her partner, mischief and pleasure written all over his face.

"Ready to go?" he asks, and Kate feels the flush rising in her cheeks. She wonders...

"How long have you been standing there, Castle?" she asks, menace dripping from every word.

He grins and holds out her coat.

"Wouldn't you like to know?"