A/N: Prompted by a tumblr picture post of art made by angelcosta78 (click the "cover art" on the left to see a larger version). Just a bit of speculation on my part, not related to any canon.
Contrary to television memes, neither writing nor law enforcement is, strictly speaking, a "day job". Rick has his routine, his own disciplines, to ensure that he writes every day no matter where the words end up. Sure, he's up till the wee hours sometimes, when inspiration stirs him thusly. And he's been known to get up in the middle of the night to scribble down an idea that he hopes makes sense when the sun is up.
Kate's content with a crazy schedule, herself. She knew when she became a cop that her time would not be her own on a regular basis; she goes out on cases, or to the precinct or the morgue, or just upstairs to the spare room where she's cobbled together her own office, whenever duty calls.
They both hate it when their respective duties call out of synch. Like this past week - Kate's been on a case where the suspect seems to be strictly nocturnal, as do his victims, so she sleeps during the day and works overnight. Rick refuses to take advantage of her presence in the way he'd like to - he knows that sleep is what she needs to do - but he spends more time writing off-site so as not to disturb or distract her.
He's in the Old Haunt, chatting with the staff the night before he has to leave town for a few days, when he gets a text from his wife.
Hey good lookin…all quiet on the western front…for now
He grins to himself and texts back.
Don't jinx it. Should I head home?
Her reply is immediate, as if she'd already been typing.
Rick looks up to see the bar manager and accountant smirking at him. He smirks happily in return and rises from his seat, saying, "Don't wait up for me."
He's in a cab halfway home when his phone rings; she's calling, not texting.
"Is this Mrs. Castle?" he purrs, but he's met with a far less heated response than he'd hoped.
"I have to go to the precinct," she says baldly. "Suspect in custody, behaving badly, blah blah blah."
"You want me to meet you there?" Rick rapidly calculates the hours until he has to board a plane tomorrow morning.
"No, better not. You're leaving early, and I don't know how long this is going to drag on. Gates is determined to observe every move everyone makes, herself, and it just slows everything down."
Not to mention Gates' continuing, though diminished, disdain for his presence in the precinct, Rick thinks. He doesn't want to add to Kate's obvious frustration, so instead he says, "It is what it is, sweetheart. Listen, when I get back and your case is wrapped up we'll lock the doors and give each other the attention we've been saving up, huh?"
"Don't know if you could handle the amount I've been 'saving up', Castle."
She sounds a bit more like her usual bantering self, so Rick says hopefully, "I don't suppose we can fit in a quickie before you have to go to work?"
"Don't torture me," she groans. "Where's that time device when you need one? Don't answer that."
They end the conversation with a laugh. By the time Rick gets home, sure enough, there's no sign of her at the loft. Glumly he packs his bag for the morning and sinks into a too-large bed with a Kate-shaped void beside him.
They talk and text every day. Kate's case is solved and bundled up and shoved along in the system. Rick makes the rounds of business meetings in Chicago, goaded by Gina in a familiar form of the stick-and-carrot metho. After three nights in the wrong bed he throws everything into his bag and heads for O'Hare, his obligations fulfilled, time served.
Boarding now, he texts Kate late in the day. It's even later in New York, but he knows she leaves her phone on when he's out of town, 24/7, even if she's home asleep. Which he hopes she is, because she needs it, but she must really be out, because he gets no reply.
Of course, gremlins appear in the form of various delays and flight schedules, so their plane sits on the runway for nearly as long as the flight itself would take. He charges his phone and plays Fruit Ninja and Angry Birds and tries not to worry about Kate, beyond texting her about the delay.
By the time he reaches the loft, it's nearly midnight. He makes a fairly quiet entrance, leaving his shoes and bag next to the stairs, and pads upstairs to see if Alexis is home. She is, and asleep for a change instead of burning the midnight oil. He kisses the back of her hand, as it's the only part of her he can reach without excavating her from her covers, and sneaks downstairs to head for his own bed.
Which, gloriously, contains his own true love. He takes the path through his office, as the door is open and the ambient light helps him navigate, and he can see her tumbled hair and one long leg escaping from under the covers of their bed. Home at last, he thinks, wasting no time in slipping off his jacket and pulling airline stubs and other crumpled receipts from his pockets, laying them on the desk ready for him to address later.
His desk, though, is occupied by a black bulk that takes him a moment to identify. His old manual typewriter - well, not one he ever really used, but it's a beloved artifact and it doesn't usually live on his desk. He can't imagine what Kate or Alexis would be doing with it, and his curiousity gene takes over and leads him to turn on the desk lamp.
He doesn't have to look far. There's a piece of paper neatly rolled up on the platen, with one sentence typed out clearly. Two words (three if you count "I'm" as "I am", says his writer gene), and the traditional hugs and kisses inked after them.
I'm pregnant xoxo
All he can do is stand there, his mouth hanging open on a laugh or a gasp or who knows what might come out, until he hears a soft shuffle to his left and a sultry, sleep-laden voice.
"We meet at last."
Kate is coming through the doorway from the bedroom, and she laughs with delight at the look that he must have on his face as she wraps her arms around his waist and beams up at him.
"How long?" he manages to say, and as always, she knows what he's asking.
"I've been wanting to tell you for nearly two weeks. We just kept passing like ships in the night, and I didn't want to just text you or blurt it out on my way out the door."
She lays a finger briefly on the carriage return of the sleek machine.
"I hope you don't mind. I thought this was appropriate."
He finds his voice then, as he pulls her - them! - into his embrace and murmurs into her hair, "It's perfect."