It's pure nostalgia that makes him double back after passing Remy's.
It's not until he's retracing his footsteps that he realises his stomach is growling, and that the boys could probably use a pick-me-up, given that this case looks as though it could have them working late.
He struggles to recall the last time he ate at Remy's, deducing that it must have been years ago, when he was still working robbery at the twelfth. His mouth waters at the memory of their burgers as he pushes open the door to the unassuming diner, glad to be escaping the cold weather.
He places a to-go order and hovers near the entrance as he waits, revelling in the way the diner hasn't changed in the slightest. The décor, the atmosphere, it's all exactly the same. It's bustling, just as he remembers, and though the chatter and ambient noise blurs together, her voice cuts through the static.
"Hey! Eat your own fries."
Her tone is more playful than indignant, but he's struck by the realisation that he knows this woman.
There's something about her voice that triggers a memory that won't come into focus, and he drops his gaze to his feet as he tries to determine how he knows her without turning to see her face.
"Mine are all gone. What happened to the concept of 'what's mine is yours'?"
"I don't remember putting that in my vows," she teases, the end of her sentence inexplicably muffled.
"If you think you can distract me, you're mistaken," she says after a long pause, as he's realising that her husband's voice is familiar, too. Somewhere in the recesses of his mind he knows that he's met them both, yet their identities continue to elude him, so he turns his head slowly in their direction.
Out of all the possibilities he considered – every neighbour, every family friend, every acquaintance – Kate Beckett and Richard Castle didn't cross his mind once.
Castle looks almost the same, the years that have passed evident in the creases around his mouth, the lines on his forehead, but Kate…
He couldn't place her voice because it bears no resemblance to the carefully spoken detective in his memories.
This Kate is carefree and playful, and her eyes are shining with such joy that it's almost blinding, especially in combination with the wide grin on her face as she reaches across the table, twining her fingers with her husband's.
She's still the fierce detective he knew, if the rumours that circulate between precincts are anything to go by, but here, outside of work, there's no trace of the hardened cop. Here, she's a woman he only ever saw in faint glimpses, and now she's displaying it for the world to see.
She's happy.
He remembers questioning her relationship with Castle on more than one occasion, and when he heard of their engagement, he felt vaguely vindicated that his suspicions weren't unfounded.
He didn't, however, imagine that their being together would look like this.
Two people so enamoured with each other, finding such joy in simply sharing a meal, basking in each other's company.
He knows now that it's rare, and his heart swells, glad they've both been able to find something he's still searching for.
His name is called and he collects his order, tempted to be polite and at least say hello on his way out, but a final glance in their direction supports his eventual decision to refrain.
They're completely oblivious to the world outside the bubble of their table.
Castle's hands dance teasingly around her plate, vying for stray fries, and after a few moments of battle she rolls her eyes, pushing the plate to the centre of the table and leaning forward to brush a kiss to the corner of his mouth.
Tom Demming smiles softly at the sight, at the evidence that such all-consuming love exists, the confirmation that it can incite such unmistakable happiness, and he exits the diner, warmed by the knowledge as he embraces the cold.
A/N:
Prompt: "Set season 7 or later, post-marriage, Rick & Kate run into one of their ex's (Sorenson, Demming, Meredith, Gina, etc), and the ex is struck by their happiness, how they are with each other, how meant-to-be they are." Submitted by carolinad423.
Filled as a gift to thebeatgoeson29, via a generous donation from Hope (tshlw) to YoungStoryTellers dot com slash ThankYouTerri. See all the prompts and fills at ThankYouTerri dot tumblr dot com.