A/N: inspiration (of sorts) struck me way back in February, when i was looking for a birthday card to send to my dad. i COULD NOT figure out a way to make it work in a story, until the finale aired and we learned that Beckett and Castle would be apart for the summer. so yay for that at least, lol.

disclaimer: yes, another post-finale fic. no, i don't own Castle. borrowed a line from What I Like About You, and the title is a line from the song "The Letter" by PJ Harvey.

Kate Beckett sighed heavily as she stepped inside "her" apartment. That's how she'd come to think of it – as "hers." Because even after months of living there, she didn't really consider it to be her own. Her apartment had been blown up. This one was just a temporary place of residence, not a home. A home has that lived-in feel. A home holds all the stuff that's important to you, not just the stuff that survived an explosion. And inside a home is a person or two that care about you, if you're lucky. And, of course, this train of thought always led her back to him, which never made matters any better.

It had been almost a month since he'd left for the Hamptons. One long, not fun, painful, tear-your-hair-out-of-your-head kind of month. The lack of his entertaining antics aside, Kate also had to deal with what she begrudgingly allowed herself to call heartbreak. It made her furious to think of it like that; they hadn't even been a couple, and Kate Beckett does NOT fall in love before being in a relationship. But after living for a week with the ever-present dull ache in the pit of her stomach, she'd finally accepted defeat and had a good cry, her second in as many weeks. The man was turning her into a damned human Niagra Falls, and she wasn't sure who she was madder at: him, or herself.

Three weeks later, most of the anger had dissolved, and she got around to just plain old missing him. And it sucked.

To make matters worse, it was almost as if he'd fallen off the face of the planet. Her phone remained devoid of any calls or texts from him, and she'd even stooped low enough to checking his Twitter. One tweet, posted in late May, was all about how Gina was "cracking the whip" – that skank. She had furtively hoped that the whip he was talking about wasn't literal (or sexual), though lord only knows what those two were doing out there. Seeing evidence that it was hard for him to leave the city, however, lifted her spirits significantly, as did his wish that he could rewrite parts of his life. It's not that she was glad he was at least mildly unhappy, she just wanted him to be happier with her than without. Assuming that's even what he was talking about, of course.

Dragging herself back to the present, Kate tossed her keys and bag onto the table, and sat down to go through her mail. There was nothing particularly surprising in the pile, just a couple of bills. Until…

She sat up straight. The last letter in the pile was postmarked from the Hamptons.

She took a deep breath to try and still her suddenly thundering heart. It's nothing, she told herself, all the while picking nervously at a corner. The envelope is too small for it to hold anything important.

Slowly and deliberately, she turned the envelope over in her hands. She ran her thumbnail underneath the flap to break the seal, and gingerly pulled out the card.

Damnit, were her hands shaking?

She took another deep breath before looking at what she held in her hands. It was a multicolored striped greeting card. In the center was a picture of a young, pigtailed, brightly-smiling girl next to a printed caption.

"Pigtails are just about as much fun as hair can have. It's like a party for your head!"

Kate grinned, and opened the card. Printed inside was, "Happy Birthday. Wear the pigtails."

Underneath, in Richard Castle's neat scrawl, was a handwritten message.

"Okay, so it's not your birthday. But it made me think of you."

Kate didn't even care that she couldn't wipe the smile off her face.

::::::::::::::::::::::::::::::::::::::::::::

"Richard! Where are you?"

Rick rolled his eyes. "I'm in the kitchen, Gina," he called back. "Ya know, even writers have to eat sometime."

He heard the click of her heels on the tile of the entryway. "I have to go out, I have a meeting. Is it safe to leave you here alone?"

"If by that you mean to ask if I'm going to get any writing done, than yes, it's safe."

She poked her head into the kitchen and peered at him over her sunglasses. "If there's not a new chapter by the time I get back—"

"Gina. Leave."

She glared at him, but retreated from the room. He let out a long breath when he heard the front door open and shut behind her. And so had gone their previous month together. If he hadn't been sure the divorce was a good idea before this summer, he most certainly was now. The woman was impossible.

Meandering over to the fridge, Rick glanced at the neglected pile of mail sitting on the counter. He hesitated, and thought back to a week earlier, when he'd decided to send Kate a card. He'd stumbled across it when he was at the local drugstore and spent several hours thinking of a reason to send it to her. He'd finally decided that it could be for no reason other than that it was too perfect not to send.

And maybe because he missed her. But just a little bit.

He often wondered how she and Demming were doing. There had been countless times where he'd wanted to call, or text at the very least, but didn't want to get her in trouble; Rick had been on the overprotective boyfriend side of things before, and he knew that no man in his right mind would want Kate Beckett texting anyone but himself. So he'd held off, for her own good. This card, he'd decided, was perfectly safe – an inside joke, so it was very much appropriate, but at the same time should give her an inkling that she was on his mind. And, just in case it didn't, he'd written it.

Now, he'd reached the uncomfortable stage of knowing that the card should've arrived by now, and that he could be receiving a reply at any time, if he was going to be getting one at all. He told himself not to get his hopes up, but that hadn't stopped the little flicker of 'maybe today's the day' he felt when he woke up each morning.

Abandoning his journey to the fridge, he headed instead to the mail pile. No harm in checking, right?

Yet again, he was sorely disappointed by the lack of Kate. Making a face, he turned the latest issue of Cosmo (Gina's contribution to the household) sideways and shook it to make sure nothing was stuck inside.

An envelope addressed to him, in the handwriting he knew so well, slid out and landed face up on the counter.

Like a kid on Christmas morning, he grinned and dove at it, ripping the envelope open as quickly as possible, all too eager to see what it held. He found himself looking at a black card with a gray prison cell on it.

"Being known as the 'fun one' of the group is a good thing. Unless you're in prison."

He laughed happily, and opened the card, where it continued, "Happy Birthday. Avoid prison."

His smile only grew wider as he read what she'd written underneath. "Funny, 'cause this one made me think of you."

Suddenly, a brilliant idea came to his mind, an idea that made his stomach flip at the mere prospect. He quickly pulled the nearest pad and pen towards himself, and wrote a short message.

"Will you be my pen pal?"

Underneath, he drew three boxes; one next to "yes," the second next to "no," and the third next to "I'm rolling my eyes at you."

After a moment's hesitation, he added another sentence at the bottom: "Check one (or two, 'cause I know you want to)."

::::::::::::::::::::::::::::::::::::::::::::

Kate chewed on her lip as she looked at the piece of paper on the table in front of her. When she read Rick's message, she'd immediately rolled her eyes… and then quickly checked "yes." Grinning at how well he knew her, she checked box number three as well. But now that she'd had a few moments to think about it, she'd become a little unsure. Not about her choice to accept, but about what she was going to say.

Seriously, what the hell was she going to say? 'I broke up with Tom for you, and then you left to spend the summer with your ex wife' sounded, to Kate, a little too direct. 'I miss you'? A little too clingy. And 'hope things are going well with Gina' was just a big fat NO.

Finally making up her mind, she scribbled her return message in the margins of the paper he'd written on.

"I haven't had a pen pal since the fifth grade, so I'm a little rusty. Does the man who writes for a living mind kicking things off?"

::::::::::::::::::::::::::::::::::::::::::::

"Dear Kate," Rick wrote. He paused, wondering if that was an acceptable greeting, but shrugged it off. There's no way he'd be calling her Beckett all summer.

"Ooooh, you had a pen pal in fifth grade? Do tell!

To be honest, I haven't had a pen pal in eons either. Not since Reagan was in the White House, I believe. And even if I had, I'm not even really sure that experience would set a good precedence for this one. I mean, we already know each other (and pretty well, I might add), so there's no need for that awkward 'what's your favorite color?' stuff. (But, in case you were wondering, it's purple. Don't judge me.)

So now that we've got that out of the way, how's your summer going? Have I missed any interesting cases? I almost forgot how dull my life is when I don't spend it with real criminals – they make the imaginary ones that much less exciting. But, since Gina's cut off the internet, I have nothing to do but think up ways to make them interesting.

Yes, you read that right; Gina cut off the internet. I'm basically under house arrest, and seriously considering throwing myself through a window to escape. If I suddenly show up at your door looking like I've just walked the entirety of Long Island, you'll know why.

Sorry, I didn't mean to word vomit my complaints all over you. Please, do me one better, or I'll feel really bad. Wait, no, if you do me one better, that means you're unhappy, and I don't want that either. So just tell me something. Anything.

Waiting by the mailbox,

Rick"

::::::::::::::::::::::::::::::::::::::::::::

"Dear Rick,"

Kate paused, wondering why that greeting flowed so easily from her pen. She'd called him Rick in person maybe twice, always in jest, and it seemed very odd that she'd have no problem documenting it now. She shrugged, and went on.

"Don't apologize for word vomiting. It's basically what a pen pal's for. So for future reference, feel free to complain to your heart's content, because trust me, I fully intend to make my letters worth the insanely high cost of a stamp. Gotta love living on a cop's salary, yes?

And please, purple is the color of royalty. With a name like Castle, isn't the royal color very fitting?"

Kate filled the next page and a half with surprising ease. She hadn't wanted to talk about work, but hey, he'd asked…and she couldn't deny that she wanted his input. Not even for help solving the case (with any luck, it'd be solved before she'd get his response), but just for his wisecracks. And to see how his mind worked – she couldn't help but be interested in his thought process.

What she studiously avoided mentioning, however, was the fact that she was no longer with Tom. Her spirits had been lifted immensely by his mentioning how unhappy he was with Gina, but until he specifically said that there was nothing going on, her own relationship status was going to remain confidential. Childish? Yeah, maybe. But she'd be lying if she said the sting of his leaving wasn't still slightly present.

::::::::::::::::::::::::::::::::::::::::::::

By the time the dog days of summer had the island in a chokehold, checking the mail had become Rick's favorite time of day. He and Kate had been writing regularly, sending and receiving at least one letter per week. Oddly enough, even though they'd been apart since the end of May, Rick felt closer to her than they'd ever been before. As much time as they'd spent together, most of it had been in the professional capacity. But now he was getting all sorts of glimpses into her personal life that he hadn't gotten before, and he was loving every single one.

In one letter he received in mid-July, a paragraph ended abruptly in the middle of a sentence. On the next line, a new paragraph was started, in a different color pen. "Damn," she'd written, "I got called to a crime scene and totally forgot what I was trying to say earlier." Rick was smiling about that for hours after he'd read it.

There were letters with little splotches of coffee or a sauce on them, which had him imagining her writing as she sat at her kitchen table and ate dinner. There were letters that were a little crinkled at the corners, which made him wonder if fiddling with the paper was a manifestation of nerves as she was thinking about saying something personal.

But then there were the letters that did say something personal. "It would've been my mom's 54th birthday today," she wrote in early August. "I've finally gotten to the point where I can sleep soundly the night before, but there's still a dark cloud hanging over the day, without fail." The thought of her so upset gave him a strong urge to drop everything and drive (screw that, fly) back to Manhattan to give her a hug. But the realization that he'd have to go through Gina to get the car quickly deflated that impulse.

Of course, he enjoyed hearing about the cases she was working as well. He knew that she'd most likely receive his input too late to actually consider it, but he found it immensely refreshing to spin a story not related to his book for a change, and to someone who would take him seriously. If his theories did end up helping, than all the better!

But what jumped out at him most is that not once had she mentioned Demming. There were a number of times where he'd been on the verge of asking how they were doing, but had restrained himself. He'd consoled himself by repeating the mantra 'no news is good news.'

::::::::::::::::::::::::::::::::::::::::::::

Kate couldn't believe how fast the summer had gone. Having something to look forward to every time she checked the mail really helped time fly, and she was able to escape the tedium of her daily life for several hours a week. It certainly didn't hurt that the man she was writing to was completely butterfly-inducing.

Maybe it was just her imagination, but Rick's letters brought with them the sights and smells of the beach. The salty breeze, the warm sun, sand underfoot, scores of beautiful beachgoers… alright, the thought of Rick surrounded by bikini-clad women made her slightly nauseous. But if he was spending time writing his book and writing to her, he couldn't have too much time for beach skanks or a certain blonde wearing head-to-toe pink, could he?

If he'd been spending any time at the beach, he certainly wasn't letting on. When he spoke of what was going on in his life, he wrote only of his book. She was glad he was getting a good amount of work done, and loved when he worked through plot points in his letters. By this time, she'd figured out a decent portion of the case Nikki Heat would be working on, and let Rick know. "Hm, now you've become a liability," he wrote in response. "You'd better burn my letters! Or else keep them under lock and key, but I'm not nearly optimistic enough to hope for that."

Reading that brought a blush to her cheeks. In fact, she had been keeping them all.

Kate couldn't remember the last time she felt she'd gotten to know someone so well. She found that writing letters added a whole new depth to their relationship, and loved the insight she was getting into what really made Rick Castle tick.

Every now and then he'd mention his mother and the work she was doing on her new play. "After a bad couple of years, I'm really happy that she's getting her life together," he'd written. "It's still weird at home without her, but Chet seems to be a decent guy. And, at the risk of sounding like a complete sap, I'm proud of how she's gotten her career back on track. Does this make me a total mama's boy?"

Kate had giggled, and responded, "Maybe a little. But I don't mind."

He also dwelt a lot on Alexis. "I talked to Alexis on the phone today," read one of his earlier letters. "She's absolutely loving Princeton. I think I could handle it if she decides to go there for college. After all, New Jersey is much closer than England. You knew she's been considering Oxford, right? Maybe that was her plan from the get-go! See, now every school in the country sounds good compared to letting her go overseas. Wow, I might have a truly diabolical daughter on my hands. I don't know if I've ever been so proud."

The fact that she was never entirely shocked about what he wrote about made her pleasantly content – they already knew each other so well. Of course, there were little things she learned about him in each letter, like how winter is his favorite season, and that he secretly watched stupid Vh1 reality shows when he couldn't sleep.

But the one thing that really made her pause came in a letter in early September.

"Naked Heat is finally done, and off to the editors. Could the 12th precinct stand to gain a consultant back?"

::::::::::::::::::::::::::::::::::::::::::::

Lanie Parish hummed slightly as she worked on her latest body, holding a scalpel delicately in her right hand. It was early morning, and most other medical examiners were still not in yet, leaving her to work in peace and quiet.

She nearly jumped out of her skin when the doors to the morgue burst open and Kate Beckett strode in.

"He's coming back today," she said by way of greeting.

Lanie put a hand over her pounding heart. "Christ, girl, you sure know how to give someone a heart attack. I almost decapitated Mr. Lester here."

"Sorry," Kate said, looking slightly guilty. "But this is an emergency."

"Well, this corpse isn't yours, so I imagine it's an emergency of the personal sort?"

Kate nodded fervently.

"Alright, now that I can hear over the pounding of blood in my veins, what's the emergency?"

"Castle."

"What about him?"

"He's coming back today. That's why I'm here so early, I needed to talk to you before he gets here because I don't know what to do."

Lanie looked at her clearly anxious friend and sighed. "Based on the look on your face, your feelings about him haven't changed?"

Kate bit her lip, and shook her head minutely. "Not… not in the way I hoped," she said in a strangled voice.

Lanie's scalpel clattered onto the table. "What do you mean not in the way you hoped?"

"Um," Kate said awkwardly, "We've sort of been… writing to each other."

"Writing to each other?" Lanie asked incredulously.

"Yeah. Like… pen pals."

"You've been pen pals…"

"Yes."

"With Richard Castle…"

"Yeah."

"For the entire summer?"

"Uh huh," Kate answered nervously.

"Not even touching the fact that you've been keeping me in the dark about this – which you're forgiven for, by the way," she added, looking at Kate pointedly, "let me just make sure I'm hearing this correctly: you're more into him now than you were when he left?"

Kate bit her lip again, and looked as if she had to force the words out. "I think so. A little bit. Maybe. Yeah."

"Even though he left?"

Kate sighed and shrugged sadly. "He thought I was with Tom. Honestly, in hindsight, I can't blame him."

"Is he with his ex?"

"He never really said, but he wrote about what a bitch she is on multiple occasions."

"Okay, let's take that as a 'no.' Does he know you're not with Tom?"

An awkward silence filled the morgue.

Lanie groaned. "Really? You didn't tell him?"

Kate scratched her head awkwardly and looked up at the ceiling to avoid eye contact. "No…"

Lanie wanted to smack herself in the face. "You're impossible."

"I know, I'm sorry."

"So let me get this straight; you're single. He's single, or else very unhappy with what's-her-face—"

"Gina," Kate supplied bitterly.

"Okay, Gina," Lanie amended, "But as I was saying, you're single. He's single, or as good as. You're basically in love with the man. And you've been writing to each other for months, which implies there are feelings on his end too."

"Sounds about right."

"And now you're here, on the day he's coming back, asking me what you should do?"

"Yeah?" Kate answered shiftily.

Lanie smacked her arm.

"Hey!" Kate cried.

"What the hell is wrong with you?" Lanie exclaimed, smacking her once again.

"Lanie! What are you doing?"

"Finding out what the hell is wrong with you!"

"Wha—?"

Lanie held up a hand to cut her off, and pointed to the door with her other hand. "Go. Back to the precinct. Right now. You are going to tell Castle how you feel, maybe make out with him a little bit, and put both of you, and everyone else, out of our misery."

"But Lanie—"

"Go!"

"But what if he is with Gina?"

Lanie sighed, but couldn't keep a smile from seeping onto her face. "Honey, if he was with another woman, he would not have spent his summer writing to you."

Kate hesitated, but finally grinned and pulled her into a quick hug. "Thank you."

"You're wasting time!" Lanie said, batting her away and shoving her in the direction of the door.

"Okay, I'm going!" Kate laughed, turning her stumble into a jog. "Wish me luck!"

"You don't need it!" Lanie called as the doors swung shut. She looked heavenward. "Just please end the madness."

::::::::::::::::::::::::::::::::::::::::::::

Kate's heart was beating furiously as the elevator doors opened and she stepped out into the bullpen. Her eyes were immediately drawn to the back of a very familiar head sitting in the chair next to her desk. She couldn't help but smile, and took a deep breath. Here goes nothing.

Her excitement to see him again began to overpower her nerves as she approached her desk, and she couldn't help but feel herself falling right back into their old ways of playful joking.

"Anyone else have this weird sense of déjà vu?" she asked no one in particular, stopping next to his chair.

She grinned as he leapt to his feet and turned to face her, looking equally as happy as she felt.

"Hi," he said breathlessly.

"Hi," she answered softly.

They didn't say anything for a few seconds, just stood there looking at each other happily. Finally, Rick cleared his throat nervously. "I'd hug you hello, but I wouldn't want to get you in trouble."

Kate's brow furrowed. "In trouble?"

"Yeah. Ya know, with Tom," he clarified.

Oh. She shot him a small smile. "That's not an issue anymore."

He raised his eyebrows. "Oh? Do I need to beat him up?"

She chuckled, and shook her head. "No."

"What happened? I mean," he added hurriedly, "I don't want to pry, but you seemed to really like him…"

She shrugged, and repeated the words she'd said to Tom. "He just isn't what I'm looking for," she said, meeting Rick's eyes and praying that he'd get the message.

"Oh," he said softly. After pausing for a beat, he smiled and opened his arms. "In that case…?"

She smiled and stepped into his embrace, sliding her arms around his neck as his wrapped around her waist.

His smell had been almost literally burned into her memory from the night her apartment had been blown up, when she was wrapped in his jacket and his arms as he helped her to safety, but she drank it in anyway. She sighed into his shoulder, reveling in his solidity and the way he held her like he never wanted to let her go. Allowing her eyes to slip closed, she thought hazily about how a hug this long may not be socially appropriate. That notion was quickly chased out of her mind by an entirely more pleasant one; I could definitely get used to this.

"Did you burn my letters like I told you to?" Rick whispered conspiratorially into her hair.

"No," she murmured, smiling. "Kept them all."

She felt him smile. "Even better."

She pulled back and met his eyes again, and was suddenly hit by a wave of butterflies in her stomach. It was one of those things that, if she told Lanie, her friend wouldn't understand the magnitude of what was happening. It had always been that, with Rick, what was said was often less important than what was not said. He had a way of looking at her that made her go weak in the knees, and the way he was looking at her now… well, suffice it to say that Kate knew something in their relationship had shifted.

She swallowed hard and willed her heartbeat down to a normal rate. "So. You ready to help me catch murderers again?"

"That all depends."

"On?"

"On whether or not you let me make you dinner tonight."

She smiled. "I think we can make that happen."

"Good," he said, eyes twinkling. "Than yes."

She reluctantly stepped out of his arms (she was here to work, after all). He slid his hand down her arm as he released her, catching her hand and squeezing it briefly before letting go. Her heartbeat, once again, rocketed skyward. Turning back to her desk, she spotted her mug next to her keyboard, filled with still steaming coffee. Oh, how she'd missed that.

"Is everything okay?" Rick asked, noticing that she'd suddenly gone very still.

"Um, yeah," she answered, making up her mind very quickly, her back still to him. "Just forgot something."

"Hm?"

Before she could convince herself otherwise, that it was a bad idea, that people were watching, that she was acting too rashly, she turned back around to face him and kissed him quickly on the lips.

She held in a giggle at the gobsmacked look on his face.

"What was that for?" he asked, a smile slowly spreading across his face.

She shrugged. "You brought me coffee," she said, shooting him a lingering look as she turned back to her desk. Shuffling through case files, she grinned as she heard him let out a breath.

"I'm suddenly much more excited to make you dinner," he mused.

"Assuming that your effort and my reaction have a direct relationship, are we? You know what happens when you assume."

"Yeah yeah, I make an ass out of you and me. Well, just me, actually."

"Hm," Kate mused slyly. "Well, lucky for you, I like yours."

Feeling very lucky he couldn't see her face, she grinned at his silence.

"Did you — just — say…" Rick stuttered, "that you like my ass?"

"Yes, I believe I did," she said, turning to face him and patting his shoulder. "Do try and keep up, will you?"

"What is this alternate universe?" he said in a hushed voice, "And where has it been all my life?"

She smiled. "Hiding in a package of filler paper and the most perfect card ever."

His eyes lit up. "Why, Detective Beckett, did my letters woo you?"

She raised an eyebrow.

He sighed happily. "Welcome back to me!"

FIN.

A/N: most fitting greeting cards ever, yes? haha. i'm not sure what i was expecting when i started writing this, but this final product was certainly not it! i like it well enough, though, and hope you do too! :]