A

They're looking for a murder suspect with a big black dog when Castle lands an obvious Hound of the Baskervilles reference.

Kate blinks at him. "You've read that?"

"Are you kidding? I read it when I was twelve," he chuckles. "It's one of my favorite novels. I finished the entire Sherlock Holmes canon before I finished high school."

"Huh."

"What?"

She shakes her head. "Nothing."

For some reason, she hadn't realized he's as avid a reader as she is.

B

His eyes are impossibly blue, and the first time she catches herself staring at them, Kate tries to pass it off as a simple unconscious glance.

The second time, she tells herself to stop doing that.

After the fifth time, she stops counting.

C

She's charmed before she even realizes how charming he is.

Kate has dealt with her fair share of absurd, ridiculous, handsome men. It's not news to her that sometimes a handsome man will use his charm to his advantage.

With Castle, though, it's different. She can't quite explain it. Maybe she doesn't want to. But he's a baffling mixture of direct and roundabout, from I'd be happy to let you spank me to silently refilling her coffee before she even realizes it's getting low. She's normally more guarded than this. Kate doesn't let people get under her skin so easily.

She probably should have been more cautious.

D

They catch a case where they find a single witness: a little boy who's terrified. It takes him hours to open his mouth at all, and even then, he's monosyllabic.

Kate's impressed with Castle. He's amazing with the boy, talking to him, trying to set him at ease. It's a level of patience she hasn't seen from him, and it's really something.

Castle steps out of the break room as the boy's mother goes in to talk to her son, and Kate puts her hand on his arm. "Hey. You've been great with him. Thanks."

He looks down at her and she's stunned. There's something in his eyes she can't quite get. None of the mirth she expects from him. Just determination.

"He saw something terrible. I just hope he's okay."

Castle moves away, leaving Kate to stare after him, wondering what long-ago darkness he's remembering.

E

"Good morning, Detective."

Kate gives him a tired smile from her perch on the edge of the desk. "Morning."

"Late night or early morning?"

"'Or?'"

He winces, settling beside her, looking up at the murderboard. "Yikes. Maybe this'll help."

Castle hands her a cup of coffee. She opens her mouth to say thank you, but when her fingers brush over his, she takes in a sharp breath.

Whatever this is, it's electric.

F

It's one of the rare occasions she's at his loft, watching him pore through some old list of contacts, when she notices a photo on his desk.

It's a picture of him and a tiny little Alexis, a precious little toddler with long red pigtails and a bright smile. She's perched atop her father's shoulders, clinging tightly to his hands, and the two of them are in front of some building that looks like a jumble of colorful blocks.

"Cute picture, isn't it?"

Kate glances up, startled, but Castle's smiling at her. "When was this?"

"Twelve years ago, maybe? My mother took it." He smiles. "We were in Rochester, at the National Museum of Play. It's a great place."

"I'm assuming Alexis enjoyed it almost as much as you did."

He grins at her. "We used to go there every summer. Her favorite place in the world."

Castle goes back to whatever notes he's paging through, and Kate looks back at the photo, a quiet, sweet reminder that of all the things he is, the most important one is father.

G

Kate's at the end of her rope, staring at another rejected request for a search warrant. Nighttime has long since set in, and her neck and shoulders are sore. Her head aches, a slow, tight pinch between her eyes.

Maybe it's time to go home for the night.

Castle had stepped out into the hallway to take a phone call, and he walks back in now, tucking his phone into his pocket. "Sorry I was gone. Alexis says hi, by the way."

Kate smiles faintly. "Hi back. I think I'm going to call it a night."

"Okay. You do look tired."

She'd protest, but every part of her is tired, so Kate settles for standing up and reaching for her jacket, only to find Castle's already holding it up for her.

"Oh." After a moment, she slips her arms into the sleeves. "Um. Thank you."

"Sure."

He walks to the elevator with her, hands in his pockets, and only when they're on their way to the ground floor does he speak again.

"Thank you."

She shrugs. "For what?"

"For letting me work with you." Kate looks up, startled, but he just shrugs. "I really do appreciate it."

She can't hold back the smile that blossoms over her face.

He might be a handful, but she can deal with him like this. When he's simply being genuine.

H

One afternoon, while Kate pages carefully through a set of interview notes, Castle stares at her fixedly until she finally breaks. "What?"

"You were a troublemaker, weren't you?"

"I'm sorry?"

"As a kid." He settles back in his chair. "You may be the law now, but I bet young Kate Beckett was a hooligan."

Kate arches an eyebrow. "Where does this come from?"

"I'm curious." He spreads his hands. "So? I'm right, aren't I? You were a terror in pigtails?"

She smiles. He seems delighted to think she was a young hellion.

I

"Oh! Beckett!" Castle grabs her hand, pulling her back from the door. "Hold on. It's not -"

He lets go, and she looks down at her wrist to find a pattern of dark stains. Four fingers. A thumb. A palm.

"Castle?"

He looks down and winces. "I'm sorry. I was writing earlier. I didn't think to wash my hands."

Kate takes a deep breath, turning over her arm, staring at the ink on her skin. He's branded her.

It's a strange sensation, being marked with ink. With Nikki Heat's only real, physical identity.

"I'm sorry," he says again, handing her a handkerchief. "I'm an idiot."

J

Johanna Beckett would have liked Richard Castle.

The thought occurs to Kate one night as she's taking off the ring. She freezes, staring at the glint of the chain, the wink of the diamond.

Her mother had always been the lively one in the family. Johanna Beckett had possessed the brightest wit, the liveliest sense of humor. Johanna had lived her life with joy.

She'd have liked Castle. And she'd have teased Kate about it.

K

Kate's in the break room when she hears Castle's voice outside. She glances at her watch. Odd. He doesn't usually come in this early.

But rather than beeline for her desk, she sees, he's headed for the corner, where an exhausted-looking uniform, a rookie named McFadden, is sitting. The poor woman is nearly falling off her chair.

"Double shift?" he asked.

McFadden nodded. "It's fine. I'll live."

"Well, maybe this'll help."

Castle holds out one of the coffee cups he's holding. The young woman looks startled. "For me?"

"Yeah. I noticed you were stuck here."

"But - I thought - you only brought Detective Beckett coffee."

Kate huffs indignantly, but neither of them seem to hear it.

Castle just shrugs. "I'm a complicated man, McFadden."

That makes her laugh, and she takes the coffee, taking a grateful sip. "Well, that's really nice of you."

"I hope it's all right. I didn't know how you took it, so it's just -"

"It's perfect." The young rookie smiles up at him gratefully. "Thanks, Mr. Castle."

"It's Rick, officer. And no problem."

He turns for Kate's desk, and from her view in the break room doorway, Kate lets out a long breath.

Bringing good coffee to an overworked cop is the world's greatest kindness.

L

Castle's a liability.

Kate's never had a ridealong before, although she's known both uniforms and detectives who have worked with them. There are plenty of stories. Good ones and bad ones.

None of them, however, include a civilian who casually uses the mayor to force her to include him in dangerous cases. Kate's spent plenty of time gritting her teeth because now she doesn't just have to solve cases, she has to do it while keeping Richard Castle alive.

She usually tries to avoid liabilities.

Unfortunately, this one is turning out to be too likeable for comfort.

M

On May 31, Castle walks into the precinct and informs Kate, Ryan and Esposito that he's taking them to get Mongolian food for dinner later, because he checked Today in History on his phone and it's Genghis Khan's birthday.

N

"Hey, Dad."

Dad gives her a tight hug. "Hello, Katie. It's good to see you. How's work?"

After the waitress takes their order, Kate sighs and unleashes the newest story in a new series called Exasperating Things Richard Castle Does.

By the time their food arrives, her dad is chuckling, and Kate sighs. "So. That's how work is going."

Dad just smiles.

"Well. He sounds nice."

O

Kate's in the middle of eating dinner one evening when it occurs to her: Castle's open. Unguarded. Personable. Precise things she's never really been.

It's not an earth-shattering realization, but it starts her thinking. Mentally cataloguing the scores and scores of things she doesn't understand about this author who's written so many books she's loved.

She wonders if Castle's realized his new muse is his own polar opposite.

P

Kate hangs up her phone with a sigh. "We have to search the records manually."

"No computerized database?" Castle asks, surprised. "Wow. Old school."

She gives him a wry smile. "You really don't have to stay. It's a long shot at best."

"Not at all. I'm in it to win it."

"Are you sure? It'll take a while."

He fixes her with a keen look.

"I'm a patient man, Detective Beckett."

There's no reason that should have made her blush.

Q

There are many, many adjectives to describe Richard Edgar Castle.

Quiet isn't one of them.

R

After a long, tiring day of running around Manhattan trying to find people who don't want to be found, Kate collapses on her couch with A Rose For Everafter.

She's always loved this novel. It might be her favorite Castle book. And the first time she'd read it, twenty-one-year-old Kate Beckett had blushed furiously to see the dedication, with initials that matched her own. You make the stars shine.

The tone in this book has always caught her. It's warm. He wrote this when he was happy. And she knows him now, and sometimes she can imagine him sitting in his study, typing away.

She's not his KB, though. There's still a lot she doesn't know about him.

So she re-reads.

S

Castle smiles a lot.

He has the cheeky grin. The boyish, impish smirk. The I'm-excited-about-solving-mysteries beam. The I'm-Pushing-Kate's-Buttons twinkle.

She'll never, ever admit it, but his real smile - the one she sees when she smiles at him - is the one that takes her breath away. His eyes crinkle, his whole face glowing with delight, and she just can't help but grin back.

It may not be as photogenic as the glossy beauty shot on his book jackets - his publicist would never approve of so many wrinkles - but Kate likes his real smile the best.

T

Richard Castle tells stories. It's like a sickness. She doesn't think he could manage to stop himself.

One day, after he finishes spinning some long-winded, fanciful tale about their suspect and a vast Illuminati conspiracy, Kate finally sits back in her chair. "Do you even listen to yourself talk?"

"You don't appreciate my craft, Detective." He shakes his head in mock-despair. "The art of storytelling is a rich, noble, millenia-old calling. Like the wandering minstrels of medieval Europe, we ply our trade across the -"

"Yo, Castle!" Esposito yells from across the bullpen. "Less talking. More coffee."

"On it!" Castle bounces up from his chair and heads for the breakroom, leaving Kate to stare at him, wondering how it's come about that the youngest female detective in the NYPD has managed to acquire her own personal troubadour.

U

He doesn't know it, but they'd met before that night at his release party.

Kate keeps her mouth shut, but she remembers every detail. The long, long line. The tittering girls in front of her. The sharp corners of the book in her hands. The flush in her cheeks when she finally got to him.

He'd flashed her a smile, signed her book obligingly ("Who should I make it out to?" "Kate. To Kate.") But when he'd handed it back, he'd stopped to shake her hand, firm and deliberate.

"Thanks for coming in, Kate."

Kate still has the book. It lives on one of her bookshelves next to several other Richard Castle novels, a paper reminder of a day she'll always find unforgettable.

V

"It's a valid theory," Kate says.

Ryan and Esposito stare at her, then at each other. Castle holds up one hand. "Let's just hold on a moment. I think we need to acknowledge the fact that Kate Beckett just said my theory is valid."

Ryan nods. "We all heard it."

"She sure did, Bro." Esposito claps him on the shoulder. "Congratulations."

"Really, guys?" Kate sighs. "Can we please move on? Maybe, I don't know, solve this case?"

Before anyone can react, Castle slides off the desk, kneeling in front of her with a flourish. He grabs her hand before she can pull it back.

Kate freezes. "Um. Castle."

"Detective," he assures her earnestly, "you have my undying pledge to continue offering you my valuable crimefighting assistance. Forever."

W

Kate sees him writing one day in the break room.

He doesn't see her at first, so she pauses, watching. His head is bent, his face rapt with concentration. He writes quickly, hand flying over the page, and she wonders what scene he's sketching out. What Nikki Heat (that stupid, stupid name) is doing now, in the world that exists in his mind.

After a few moments, he glances up. "Oh. Beckett. Hi."

She wants to say What are you working on?

Instead, she says, "We're ready to go."

X

Xenophilia is the love of the strange. Appreciation for the unfamiliar.

Seeing Will Sorenson and Richard Castle in the same room was surreal. Her ex-boyfriend and her exact opposite. She didn't know how to deal with that.

It worries her that Castle seems to understand the situation perfectly. Ying yang is harmony. Ying ying is a name for a panda.

It didn't work out with Will. Maybe she never really needed a xerox copy of herself.

Y

Castle lets out a giant yawn. "Sorry," he mumbles sheepishly.

Kate straightens in her chair, ignoring her aching back, and glances down at the time display on her desk phone. 11:42pm.

It's almost midnight, but Castle's still here.

"Why don't you go home?"

"Are you going home?" he asks. "I thought we were working."

She bites back several pithy retorts about this being her job and him being nothing more than an observer, because, she realizes with a pang, he doesn't have to be here. He's choosing to be here.

Maybe he takes this more seriously than she thought.

"Then stop yawning. You're making me yawn."

He salutes her with an impish grin and sparkling eyes, and she's pretty sure he can see right through her.

"Aye aye, ma'am."

Z

On a rare night off, Kate and Lanie settle on Lanie's couch with wine and dark chocolate.

"I'm telling you. Stop pretending." Lanie shakes her head. "Castle's a lot better-looking than Spongebob Squarejaw was."

"Lanie. Come on. Will's not -"

"- interesting? No. He's not." Lanie shrugs. "Meanwhile, you realize you've been talking about Castle for the past hour."

"I haven't -" Kate huffed. "It's not like that."

"So why do you keep talking about him?"

"Because he's annoying. And you know I have no work-life balance."

Kate seeks refuge in her wine, avoiding Lanie's eyes. Lanie notices too much.

"Let's hear your reasons for avoiding him, then." Lanie waves her hands. "Bring them on. Let's deconstruct this nonsense.

Kate opens her mouth, but she stops.

He doesn't take this seriously. That's not true.

He's annoying and immature. He's got a sense of humor, but he's actually a devoted father.

He doesn't care about solving crimes. He's sacrificed hours upon hours, early mornings and late nights, to help her.

He just wants to get in my pants. He'd have left a long time ago if that were all he wanted.

Lanie's staring at her, waiting for an answer, but Kate's stunned to realize that the precise number of objections she has to Richard Castle is zero.