He never expected it from her.

From himself? Of course. Everyone did. And when it was his turn four or five years ago, he played out the expected stages of grief perfectly – denial, barely concealed panic, anger, brief depression, and of course - the overcompensation.

But as much as he enjoyed the playacting and the attention – although patronizing – that was lavished upon him; and as much as they both enjoyed the overcompensation (round after round after round of enthusiastic overcompensation), he knew that it meant nothing. That what they had was so much more than time or aesthetics could wear down.

Yet, here she is. Standing in front of the bathroom mirror in a black tank top and a ragged pair of flannel sleep pants, face furrowed in an untranslatable frown, fingers clenched tight on the edge of the bathroom countertop, staring herself down in the mirror.

Kate Beckett has grey hair.

And she is clearly upset about it.

"Looks like your laser vision isn't working."

She startles at his voice, her body jarring away from the countertop into a poor excuse for casual posture. She runs a hand through the hair at her scalp and huffs at him as he leans against the doorframe, smiling.

"Should've known you'd be staring."

"You really should by now." He steps into the bathroom, trying to meet her eyes in the mirror as he stands behind her. Surprise worn off, she gazes intently at the countertop, hair falling over her face as she puts away the days tools – makeup remover, facial scrub, moisturizing lotion.

"Always gonna stare. Even when you're old and grey."

At that, her head jerks up, blue meeting brown in their reflection across the sink.

She's… nervous? He doesn't expect that. He expected a glare – all narrowed eyes and flared nostrils and arched eyebrows to chastise him for ever insinuating that she's aging. But she's not angry. She looks… sad.

He tries a chuckle –it was just a joke after all – as he skims his hands over her hips and presses himself against her back.

"Relax, Kate."

She tries on a smile that is almost more pitiable than her undisguised sorrow.

"Guess I should start buying all that anti-aging crap, hm? Wrinkles are already setting in."

He turns his head to brush his lips against the offending crow's feet at the edge of her eyelid. "Good. Means I've kept you smiling all these years."

That pulls a simper out of her – a small one, but genuine nonetheless.

He wishes he could convince her – tell her how much he loves every bit of her: the parentheses of her grin, the furrow of her brow, the crinkle of her nose – and so what if those lines are imprinted in her skin if it means he can soak in the complexion of her joy, passion, and intellect even while her face is slack with sleep? He needs her to know that he can't help but paint his affection over the veins in her hands, run his tongue over the sun spots on her shoulders, and brush his thumbs across the soft striations under her belly button late at night when their daughter misses her curfew and doesn't call, wishing she was still tiny and safe and tucked away under those stretch marks instead of a spitfire of a teenager taking the world by storm.

He wishes he could make her know without a doubt that those things she thinks are imperfections are reminders of how much she's lived since she decided to be more than a girl who lost her mother.

He wants her to know that he loves her. That he loves her at fifty-five the way he loved her at thirty-five and the way he probably would have loved her at twenty-five if he had dropped the playboy persona when she was a bony little thing with a ponytail and a ragged NYPD sweatshirt handing him a Sharpie and a tattered copy of In a Hail of Bullets.

But for once, he's not sure how to say it. Not to this version of Kate who mopes in front of the mirror on a Saturday night.

Her smile fades again and he sighs into her hair.

He thought she was fine with all of it. Having the boys at forty had already forced her to acknowledge that she wasn't a spring chicken anymore, and once Alexis made them grandparents, it was impossible not to acknowledge that they were getting old. Kate seemed to take it all in stride. But with Lily looking at colleges, Lanie's recent decision to retire, and the higher ups at 1PP hinting that there are some younger detectives at the Twelfth with great leadership potential when she decides to make the jump to politics – perhaps it's just too much at once.

And now this.

She sucks in what sounds like a fortifying breath and lifts one hand to card through the hair at the nape of his neck. "I guess if you work the salt and pepper, I can too, hm?"

He presses one last kiss into her hair then turns her in his arms so he can pull her gaze away from the mirror and her body into his. "I do work it, don't I?"

She hums as she runs her hands up his chest and he feels the spark of each warm fingertip through his cotton undershirt.

"Oh, definitely. Very Clooney-esque. One might even say you're ruggedly handsome."

He chuffs a laugh and tightens his arms around her – one banding across her lower back, and the other pressing her against him, palm spanning the warm plane between her shoulder blades. Kate obliges to his coddling and lets her head drop against his shoulder, forehead resting against his jaw. One of her hands snakes up from his chest and rasps through his stubble to rest at his cheek, her thumb sweeping over his cheekbone.

He lifts his eyes to their reflection in the bathroom mirror, and the way she tucks herself into his chest sparks so many memories in him.

The way she swayed with him in a white pantsuit on a warm night in the Hamptons. The way they clutched each other as Bracken's indictments were handed down. The way she laughed into his neck after they flipped over the pregnancy test two months after taking out LockSat. The way she grounded him before his mother's funeral. The way he clung to her after she took two bullets to the vest in a shootout last year. The way she placated him when his youngest daughter left for her first date.

And now. Here. When they've both got gray hair and are realizing just how quickly the time has gone.

"It doesn't matter, honey. None of it matters. We've had 20 years and we'll have 20 more and I don't care if you run for senate or if you retire or if all your hair falls out and we're arguing over whose pillbox is whose. I don't care. All I've ever wanted is to grow old with you, Kate Beckett."

At last, she lifts her head with that smitten gaze that's reserved for his eyes only, and he swears her smile could bring him to his knees even after all her teeth fell out.

"Good. Because you're stuck with me."

With both palms cupping his face, she kisses him soundly, and as he feels her eyelashes brush against the bridge of his nose, he thanks whatever force in the universe brought them together and gave them strength to fight through everything it took to have this life with her.

She finally steps away and pads back into the bedroom, peeling off her tank top as she goes.

"C'mon then gramps, I gotta show you some things I'm still not too old for."

He grins and rolls his shoulders. Ah, yes. The overcompensation is the best part.

Wasn't a huge fan of the finale, but I'm so glad Castle and Beckett get to grow old together, hence this. Hope you guys enjoy - sorry for any grammar/spelling errors!