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

A/N Partway through my previous story, "Please Tell Me," Beckett and her brain got into an argument. I don't know how I thought of this, but eventually it led me to the notion of devoting a story to conversations between Beckett and her brain and Castle and his. There are so many instances in canon when disaster, unhappiness, misunderstanding, anger, or disappointment could have been averted if someone's brain had interceded. That's what will happen here.

She's exhausted and hungry and ticked off. "Hell of a trifecta," she says to no one but herself as she drops the bag of Chinese food on her kitchen table. "Maybe I should get a fish. Something easy to take care of that doesn't talk back to me. Which is the polar opposite of my goddamn partner, who's high-maintenance and constantly talks back." She opens the bag, lifts out containers of moo shu chicken and pancakes, and shakes out the rest: condiments, plastic cutlery and a paper napkin, a fortune cookie. "But if I got a fish, would I have to stop eating fish? I wouldn't want to horrify my pet." She shakes her head. "I don't eat it that often anyway. Maybe I could just make sure never to eat it at home and to brush my teeth right afterwards. Wouldn't want my pet to smell one of its relatives on my breath."

Don't do it, Kate. What if you forget to feed it? You forget to feed yourself all the time.

Nice. Thanks for calling me irresponsible.

You did that, not I. As your brain, I have a number of my own responsibilities, one of which is to try to save you from some of your bad ideas, the ones you have independent of me.

Look. I'm twenty-nine years old. How is that you never spoke to me until a couple of weeks ago?

Because until a couple of weeks ago I didn't need to. Not that you haven't had some bad ideas before, but you've always figured things out on your own, or I trusted you to find your way eventually.

What changed a couple of weeks ago?

The fact that you had to ask me that proves my point.

What point?

The one I'm about to make. What changed a couple of weeks ago is that Richard Castle walked into your life.

He didn't walk in. He crashed his way in. Used his buddy the mayor.

Got under your skin, didn't he?

Damn right. Like some burrowing insect. Parasite.

I've got news for you. It shouldn't be news to you, but you're already in denial. He's gotten under your skin and into your heart.

Oh, please.

Don't bother denying it.

I sure as hell do.

You two are made for each other.

Are you nuts?

If I were nuts, you would be, too.

Oh, for God's sake.

You can deny it all you want, but I'll be revisiting this issue until you come to your senses.

She pulls her hair hard with both her hands. Could you at least leave me in peace while I have dinner? She points to her plate. See how responsible I am? And sensible? There's vegetables. And protein.

Fine, fine. I'll leave you alone for now.

She fills a pancake, rolls it up, and bites off one end. Yum. It's yummy. She and Castle and the boys just closed a case of a philandering city councilman who was blackmailed and then murdered. Not, as they had at first thought, by his wife. "Although I might not have blamed her," she says, spooning plum sauce onto another pancake. Ordinarily she's pleased at the end of a case–satisfied, maybe, more than pleased, since there's nothing pleasing about homicide–at bringing someone to justice. "Nailing the asshole," as Castle so eloquently put it. Hard to believe the man is a best-selling writer.

A best-selling writer whose books you love.

Hey! You agreed not to interrupt while I'm eating.

I did, but it's exasperating to hear you pretend that you don't think he's a great writer.

Apparently that gift doesn't inevitably translate to the spoken word. Could you be quiet now?

Someone's awfully testy. But I'll withdraw for the moment.

They wrapped up the case. Good. Great. But they're at the beginning of another, one that's obviously going to last for a while. The book he's writing, with a detective based on her. A slutty detective based on her. Slutty. If that's how he describes her she must do half her work on her back. Exactly the image she has had to fight since she joined the overwhelmingly male force. She went to his book reading tonight to give him a taste of his own medicine, to question some of the appalling writing in his latest–and last–Derrick Storm book.

"Oh, you're telling me how to do my job?" he said.

"Irritating, isn't it?" she countered.

But before she could continue down that path, Martha Rodgers, Castle's unaccountably very nice mother, revealed that the Kate Beckettesque character of her son's invention was going to be named Nikki Heat.

"Nikki Freaking Heat!" she shouts at the remains of her moo shu. And did he agree to change the name? No, he did fucking not. Furthermore, he implied that there would be not just one book, but a string of them.

Time for her fortune cookie, her favorite part of Chinese dinner. Maybe it will have a soothing glimpse of the future, something to calm her down or make her smile. She snaps the cookie open and eats both halves before allowing herself the ultimate treat: reading the fortune. But when she unfurls the scrap of paper the little red letters almost set it–and her–on fire.

TRUST YOUR PARTNER! LOVE IS IN THE AIR!

What? WTAF? She's never buying food from that place again. It has destroyed fortune cookies for her, forever. She gets up from the table, puts her plate in the sink, and throws everything else in her kitchen garbage can.

Nikki Heat. Nikki Heat. She'd be very hot under the collar right now except that the dress she has on has no collar. In fact, it bares her shoulders. It's her favorite, a gorgeous pink, and she gets very few chances to wear it. She chose it deliberately for Castle's bookstore reading this evening because she knew that it would distract him. It did, she could tell, but not enough. Not enough to get him to change her name–the name of the detective in the book, who is definitely not her because she's not slutty. But of course everyone will make assumptions, once they read the book. He has a gazillion best-sellers and a lot of people will buy the book. Like half the population of New York City. Worse, the entire 12th precinct. Unless he buys copies for them, which he probably will, like that stupid espresso machine he installed in the break room. Trying to ingratiate himself with everyone. Not going to work with her.

She needs to talk to him. Not in the cozy confines of the squad car, but in the cozier ones of his apartment. She's sure it's very cozy. Very luxurious. She needs to talk to him now. She'll throw away the garbage on her way out. Very appropriate. TRUST YOUR PARTNER! LOVE IS IN THE AIR! Oh, please.

At the front door she slips her heels back on, grabs her purse, and takes the neatly knotted bag of garbage to the trash room. There. Done.

When she steps out onto the sidewalk she sees a taxi, right on her corner. Must be a good omen. She could walk to his place, but she wants to get there as quickly as possible. When she pulls up to Castle's corner there's another cab right in front of hers, but she exits first. As she heads for his door she hears the already-too-familiar voice, this time laced with surprise. "Beckett?"

"Yes?" She stops and turns around, and hopes that she sounds commanding.

"Uh, are you coming to see me?"

"As far as I know you're the only person of my acquaintance who lives on this block." It's dark. Maybe he didn't notice her wincing over "person of my acquaintance."

"Oh. Well, that's nice. Would you like to come up?"

"No."

Shit, he's making her feel guilty. He does have really beautiful blue eyes and they look hurt. She's going to ignore them.

I told you he'd gotten into your heart.

Are you not paying attention? I'm right in the middle of something here.

"I don't need to come up, Castle. I'd just like to finish the conversation we didn't get a chance to at your reading."

"About?"

"How many conversations did we have there? About the name Nikki Heat. Change it."

"I thought the conversation ended when I said that it was a matter of artistic integrity, and that if I caved on that, what would I cave on next time? What other demands might you make?"

"No, it ended when your publisher and ex-wife–who by the way struck me as extremely demanding–dragged you away by the elbow before I got to respond."

He laughs. "You're right about one thing. Gina is unbelievably demanding. Don't know how I stayed married to her as long as I did. Not that it was that long. It only felt like a lifetime."

"Nikki Heat is a horrible name, Castle. I'm going to get no end of grief for it."

"Why?"

"Why? Because it sounds like a stripper, as I already said. I've had to put up with that crap since I was in the academy. Every day."

"Do you object to the Nikki part?"

Not a horrible name, she has to admit. Perfectly OK, by itself. Kate has more weight, but God knows she doesn't want him to use her real name. "No. Nikki's all right."

"So it's the Heat part that troubles you."

"No kidding. Heat as in hot."

"No, as in cop. The slang word heat for cop springs from police cars having red lights, as I'm sure you know."

In fact, she doesn't. It embarrasses her, but she doesn't. She'd never really thought about it. She doesn't want to lie, but she doesn't want to cop to it, either. That's sort of funny, cop to it. If he could read her mind, he'd laugh.

Maybe he can.

Can what?

Read your mind.

Instead of saying something to him she gives him her death-ray glare, which is usually very effective. She can see him wilting a little.

"Listen, the character I'm basing on me is named Rook. What does that say about me? That I'm either conning someone or being conned. Not exactly flattering."

"Given that your name is Castle, I'd say it was just a synonym. Rook is a chess piece. A rook looks like a castle. Some people even call it that."

"I doubt that the majority of my readers will make that assumption. Leap. Whatever." He looks sideways, and is quiet for a moment. "Are you sure you wouldn't like to come up?" There's a softness in the question. A sweetness.

"I'm sure." Dammit, she sees his point about both names, Heat and Rook. "Uh, there's a great old place on Mulberry that's open until midnight and has amazing coffee. Want to get a quick cup?"

He smiles exactly the way Bobby McPherson had when she said she'd go to the homecoming dance with him in ninth grade. It's kind of irresistible. "Yeah." They've walked only a few steps when he says, "Caffe Roma, right?"

"Right."

"Heaven on earth," they say as one, though neither acknowledges it.

They have a good time. He asks her serious questions about police work, ones that have real thought behind them and require real thought to answer. Half an hour of him being interested and interesting and not a smart ass at all, which might be a record.

They part company on Mulberry Street. "I won't change her name, but I'll change something else," he offers.

"What?"

"Nikki won't be slutty. I promise. She doesn't need to be. She's not just smart, she's brilliant." He stretches out his hand to her. "Deal?"

"Deal," she says, very aware of how smooth his skin is.

Forty minutes later, her teeth brushed and makeup removed, she's getting into bed.

Gotta say something before you go to sleep.

Fine. I'm in an accommodating mood.

I loved that at the crime scene you and Castle said, "It wasn't a robbery" at exactly the same time. It was so unexpected, and cute. And then tonight you did it again when you both said, "Heaven on earth."

Just a coincidence.

No, it was as if you were thinking with the same brain.

She squeezes her eyes shut and turns out the light on her nightstand.

It's after midnight, and he should be in bed, but he's still wired. Beckett asked him out for coffee! And she was right: Nikki Heat being slutty would give her all kinds of trouble, which she doesn't deserve.

Good boy.

What?

Good boy. You came to your senses.

I'm a writer, you know. Been one for a long time. You've never butted into my life before, so why now, all of a sudden? Where were you when I needed inspiration on that last book?

I was confident that you'd realize that you needed to move on. Take some chances. You have a hell of a lot of talent and you shouldn't be wasting it. The minute Kate Beckett showed up on that rooftop three weeks ago, I saw opportunity in neon lights. I was the one that gave you that nudge: write about her.

Oh.

Yeah. Oh. And another thing.

What?

She's not like any other woman you've ever met.

So?

So, pay attention. She's the real deal. You two could be the real deal. How did you feel when you both said "It wasn't a robbery" at the crime scene? At the same instant. And then tonight, again, with "Heaven on earth."

Gotta love a woman who loves Caffe Roma.

Gotta love a woman who makes the same observations that you do. It's like you're sharing a brain.

Huh. Um, I'm going to bed.

Sweet dreams.

I hope so.

I know so. I'm your brain.

TBC