A/N: This is a follow-up to the Colors story: 'You're The Cream In My Coffee' - a Season 6 fic - so you might want to go and read that one first if you haven't already. Enjoy!

The Thin Blue Line

You scan the pharmacy shelves, head whipping back and forth over the dizzying array of pregnancy test products.

"So, Clear Blue? Or…or One Step, First Response, E.P.T.…? Castle, why are there so many of them?" you ask, looking at the plethora of tests with something close to panic. "And what is this?" you ask, picking up yet another box.

"Ovulation predictor. Don't think we need that," he says, nudging you playfully and putting the box back on the shelf.

He lets his fingers walk over the various brands and then he stops dead on one particular box.

"Oh, look, digital! Beckett, we have to go digital," he declares, reaching for the packaging that depicts a tiny liquid crystal display in the center of the plastic stick.

"Seriously? It has batteries so it must be better? That is such a boy thing to say. We're buying a pregnancy test, Castle, not a remote control car. No, I want one with little blue lines. Simple, clear…and I kind of always wanted to watch for the line appearing," you confess, sheepishly, covering up your excited grin with your hand.

"You really have thought about this, haven't you?" he teases, grabbing your other hand and tugging you to his side. He tucks you under his wing and kisses you, softly, gently, on the lips, his fingers caressing your hip.

"So what if I have?" you bluster, making a half-hearted attempt to shrug him off. "It's a…"

"Rite of passage. Yeah, I know, you said already," he nods, grinning affectionately at you.

"Yeah, well, I waited long enough. So let's just pick one and get the hell out of here before anyone sees us," you say, glancing down the aisle at a couple of middle-aged women who are nudging one another and pointing in your direction. "Because I think some of your fans might be loitering over there in the incontinence section," you joke, drawing a horrified look from your fiancé. "Just sayin'," you shrug, picking a test and turning for the exit.

"How about we get two?" Castle calls after you. "A little blue line for you and…"

"Digital for the gadget geek?" you grin, coming back to hold out the basket so that Castle can drop a couple of more tests in.

You pick up some toothpaste, shampoo, and throw a random bag of trail mix and a bottle of Clorox lavender scented bleach into the basket in order that the pregnancy tests don't look so obvious.

"The cashier won't even notice what's in your basket, Beckett," Castle whispers in your ear, wrapping his arms around you from behind as you wait in line. You can feel his grin brushing your cheek when he kisses your temple. Your shifty behavior is amusing him and you hate yourself for being such a baby about this.

"Stop humoring me," you moan, poking your elbow into Castle's stomach, feeling as if you're a teenager buying your first pack of condoms.

The homely, forty-something woman who serves you gives you a wink when she runs the four pregnancy tests (and how did you end up with four?) across the scanner; the beep, beep, beep sounding louder than ever.

"Good luck, hon," she says, once she bags up your items and hands Castle back his change.

"Thanks," you manage to mutter, cheeks flaming.

You grab Castle by the hand and drag him back out into the sunshine.

"Won't notice, you said," you point out to your fiancé, rolling your eyes, unable to fight the grin that's tugging at the corners of your mouth however.

"Do you care? She wished us luck."

"Think we need luck?"

"No, I think we need to go home and get you peeing on some of those sticks."

"Castle!" you moan, wrinkling your nose, as you wait for the green light to cross Grand Street.

"What? If we're having a baby, you're going to have to get used to a whole lot more than a little squeamishness over peeing on a stick. Think total loss of dignity, Beckett."

"You're really not selling this to me at all," you tell him, as you turn into Crosby, now only a block from home.

"Any luck, it's too late to sell it to you," he grins, glancing down at your still flat stomach. "How late do you think you are anyway?"

"I…about a month," you wince, giving him a sidelong glance.

"So, seven or eight weeks since your last period?"

"Sorry," you shrug.

"Hey, not your fault. We were both…um…there, as I recall," he says, ushering you inside the lobby of your building.

"I can't believe I didn't notice though."

"Happens," he consoles you, with a squeeze of the hand. "You weren't the only one who wasn't counting. But then we have been a little busy lately, what with mother away on her cruise and the loft all to ourselves."

"Mmm," you hum, remembering one particular night a few weeks back spent rolling around on the living room floor, cushions and blankets piled up around you, flickering candles throwing long dancing shadows up onto the walls and ceiling, and the baby oil stain you had to scrub out of the rug the next day.

"Lunch?" you ask, heading over to the kitchen with the bag of groceries once you get inside.

"Lunch? Are you kidding me?" asks Castle, hot on your heels.

He swipes the bag off the countertop and steers you towards the bedroom by the shoulders.

"What? Right now?" you ask, wondering why on earth you suddenly feel like stalling, putting off doing the test for just a little while longer.

"Yes, right now. We have to know for sure. I have to know for sure," he insists.

"Why? You were fine this morning when you didn't suspect a thing."

"Yeah, well, now I do, and so I have to know, Beckett. Come on. What's the problem? I thought you wanted this?"

"I do. I do, it's just…" you sigh, running a hand through your hair and sinking down heavily onto the bed.

"Just what? Hey?" asks Castle, sitting down on the bed beside you. "Talk to me."

"What if it's negative?" you blurt, after a second or two's pause, turning to glance at him.

"I love that you want this so much, Kate. Even if it is a surprise. So, if it's negative we do what we said in the coffee shop. We throw away the pills and we have fun trying. Lots of fun trying. Now, come on. Up," he says, standing and then taking your hands to pull you up off the bed too.

You get as far as the bathroom door and then you stop when Castle tries to follow you inside.

"Oh, no. Na-huh. No way, buddy," you say firmly, shaking your head and placing a hand on his chest to hold him on the threshold.

"What?"

"I draw a line at letting you watch me go to the bathroom, Castle."

"What if I promise not to look?" he asks, trying to be adorable. "I could turn my back."

"Yeah, not happening. You can promise not to look from the other side of the bathroom door."

"You're going to have to get over this…this shyness thing if you intend to give birth, Kate."

"Yeah, well, I have about seven months to get used to that part, the way I figure it. So, deal. Outside, Castle. Come on," you tell him, shooing him away and taking the plastic bag from his hands. "Here, you can have the trail mix," you tell him, throwing the bag of dried fruit and nuts in his direction to distract him, as if he's a bear in an enclosure at the Zoo.

You sink back against the door once you close it behind you, pressing the back of your hand to your warm forehead. Then you blow out a long cleansing breath and push off the door, intending to do this thing once and for all.

"You done yet?" you hear, coming from the bedroom a few seconds later.

"Go away," you yell back. "I'm not going with you out there listening."

"Fine," you hear Castle mumble, though you don't hear his footsteps on the wooden floor if he's actually walking away.

You deposit the bag on the vanity, take out the four - yes, four – pregnancy tests, and then tiptoe back to the door. When you yank it open, Castle almost falls inside on top of you, dropping the bag of trail mix on the floor with a rustling clatter in the process, since he was leaning so heavily on the frame, his ear clearly pressed up against the wood.

"Seriously?" you glare, hands on hips, as he tries to right himself and fake looking innocent.

"Aww, Beckett, come on. Can't we just do this together?" he pleads.

"Castle, we are doing it together," you argue. "We did the…uh…deed together, and then we went to buy the tests together. Did you ever think we'd be doing that five years ago? Hmm? Look, I'll be out in a second with the wand thing and we can wait for it to work…together. And if you just give me a few seconds privacy, we'll get to that part a whole lot quicker."

"Junior isn't going to give you any privacy, I'm warning you," he fires back.

"Yeah, well, you and junior are two different people, if you get my drift. Now, just stop fighting me on this and get out," you insist, closing the door again.

Your heart is racing by the time you pull the first test out of the foil packaging. The zigzag edging won't rip properly at first, so you resort to nail scissors, your hands shaking as you try to fish it out of the little packet. You've gone with the low-tech, blue line variety you always imagined using, on the few, rare occasions that you ever imagined doing this. You read the paper instructions one more time. But it doesn't get much more complex than holding the wand in the flow of urine for five seconds or dipping it in a container and then replacing the cap, even when you read it for a second time, so there's no further reason to delay.

"Did you fall down the toilet?" you hear Castle call out from the other side of the bathroom door, and you can't help laughing when you hear his voice, how silly and eager and excited he is already, realizing with a sudden pang how excited he's going to be for the next few months if you really are pregnant.

"No. Just a second," you call out, settling yourself to do the deed, deciding to go with the container method.

When you finally open the door, your fiancé is sitting on the bedroom floor, his back resting against the wall right outside the bathroom.

You sink down onto the floor beside him, your legs now like jelly, the plastic wand gripped firmly between your fingers, the beds of your nails turning a pale shade of blue.

"Well?" he says, squeezing your knee and angling his body towards yours. "What does that blue line mean?" he asks breathlessly, leaning over your bent knees for a better look.

"That's the control line," you tell him, consulting the paperwork. "We have to wait two minutes. One minute left," you add, consulting your dad's watch.

The quiet anticipation that's ping-ponging between you makes you want to giggle. It's like a nervous tickle building low in your chest, slowly working its way up your ribcage and windpipe, until you actually begin to laugh.

"What's so funny?" asks Castle, gripping hold of one of your ankles.

"Look at us," you say, waving your free hand between you. "We're sitting on the floor waiting for a line to appear in a little window like it's magic or something."

"It is magic," insists Castle, reverently. "Not for nothing do they call this thing a 'wand', Beckett."

"Shut up," you laugh again, bumping him with your shoulder until he almost falls over sideways.

"Shhh, wait!" exclaims Castle, reaching for the wand. "Look, is that…?"

"A second blue line!" you squeal, bouncing on the floor.

"Let me see. Let me see," insists Castle, taking the wand from you, while you re-read the instructions again.

There's the control line in one tiny window and then a cross has appeared in the second larger window, one of the lines slightly fainter than the other.

"It's a cross. What does that mean?" asks Castle, grabbing for the paper sheet.

But you just let it fall to the floor with a fluttery crinkle, and you turn into his lap, cup his face in your hands and you kiss him soundly on the mouth.

When you come up for air, you rest your forehead against his, your thumbs caressing the soft skin beneath his eyes.

"That means we're pregnant, Castle. We're having a baby," you whisper, kissing him on the tip of his nose and wrapping you arms around his neck. "You're going to be a daddy again."

Tears course down your cheeks and you don't notice. Castle pulls you fully into his lap and cradles you against the wall of your bedroom, rocking you back and forth in all consuming silence.

When he finally speaks again, it's to ask you a question.

"Fancy going to get that marriage license?" he asks, kissing your hair as you rest against his chest, your eyes closed.

"It's Saturday," you murmur. "City Clerk's office is closed until Monday."

"Monday morning then. Let's do what we said. I don't want to wait anymore, Kate. I want you to be my wife."

"You're so sweet, Castle," you sing, kissing his cheek. "But I already said yes, remember?"

"Gates is going to flip," he points out, stroking your back, his fingers bumping down the ladder of your ribcage and over your sky blue shirt.

"Never mind Gates. What about Alexis? And Martha?"

"Hmm. Not sure how Alexis will handle having a sibling. It's never come up before. I'm sure she'll be thrilled."

"Really? I don't know. She's never had to share you with anyone before," you point out, skeptically.

"She shares me with you," leers Castle, nipping at your bottom lip, chasing your mouth for another kiss when you try to pull away.

"Not the same thing, daddy," you reply, patting him on the cheek.

"We're really having a baby," he murmurs, placing his hand low on your stomach and then leaning down to kiss you again; a tender, gentle, explorative kiss this time.

You sit in silence for a few minutes, time measured out by the click of the clock by the bed, and you imagine a crib sitting on your side, the warm, soft darkness of nighttime, a rocking chair to glide back and forth in while you feed your tiny son or daughter by the glow of a pale blue nightlight.

"Want to do one more test? Just to make sure?" you ask, eyes dancing with excitement, looking to Castle eagerly as you grip onto his arm.

"Digital one this time?"

"Go on then," you tell him, scrambling to get up from the floor and then offering him a hand to pull in him.

You race to the bathroom together to do this one side-by-side, chattering excitedly, your whole world about to change and expand, lives radically altered forever, both of you happier and more content than you ever thought possible, and all because of a thin blue line.

Baby blue, noun: is a color that is associated with health, healing, tranquility, understanding, and softness. Blue is considered beneficial to the mind and body. It slows human metabolism and produces a calming effect. Blue is strongly associated with tranquility and calmness. In heraldry, blue is used to symbolize piety and sincerity. Blue is traditionally considered a masculine color, with pale blue or 'baby blue' standing for an infant boy.

The 'Thin Blue Line' of the title also refers to law enforcement, both in the United States and in the United Kingdom, sometimes an actual emblem or symbol used to denote support for police - the 'thin blue line' between bad and good. Opponents claim that display of Thin Blue Line emblems is used to gain favorable treatment from officers (colloquially referred to in the United States as "flashing tin", meaning presenting a badge) in order to get immunity from traffic tickets (also known as "professional courtesy"). The imagined ability to break traffic laws with impunity has led some non-police to use thin blue line bumper stickers. As a result, their sales are sometimes restricted to those able to give a department phone number and badge number.

A/N: Hope you enjoyed that. Have a lovely weekend everyone. Liv