Mike Royce was three years from retirement, three years from margaritas on a sunset beach after a day working security in shorts and a t-shirt, when she arrived. Nothing was ever the same after that.

X-X-X-X-X

Officer Kate Beckett is fresh out of the academy, doe-eyed, and entirely too innocent to be a cop. He wonders the entire first month of their partnership why the hell a trust fund baby decided to join the police, and then one night he stops wondering. She doesn't look at him during the entire story about her mother. Her voice is quiet, wavering just enough that he's worried she might burst into tears. He resists the urge to hug her, because that's not what cops do. Especially not to their rookie trainees.

But if he's honest with himself, he falls a little in love with her that night.

The next time he falls a little in love with her is when they're working the Macy's Holiday Parade. He's pissed because he hates Christmas and people are so fucking rude and he'd really much rather be nursing a beer at O'Reilly's. He turns to ask her if she wants some coffee but she's not standing next to him anymore. He scans the crowd, calling her name, and then he spots her. She's at the edge of the crowd, crouching next to a little boy and pointing at Santa, and goddamn it if he doesn't get a fuzzy warm feeling when she shoots him a dazzling smile.

It only gets worse. She's, what, fifteen years younger than him? But when she calls him Mike every once in a while he forgets that he's older than her. He'd never admit it, not even under threat of painful death, but sometimes he says her first name out loud just to hear what it sounds like coming out of his mouth. Kate. Katie. Kate.

She changes right in front of his eyes. The months go by and she hardens, grows a shell and learns to compartmentalize. She learns the lingo, learns how to glare without being adorable. She learns to walk like a cop, but she's still got a little sway in her hips. (Sometimes he wonders if she does that for him. Then he takes a cold shower.) She's smart and resourceful. He knows very early on in their partnership that she's going places, going farther than he ever hoped to get. She's got Homicide written all over her, but Vice will get to have her first. Pretty female cop with a wicked right hook? The guys in Vice will drool over her.

But she's still Beckett. She flashes a suspect one day. They commandeer a golf cart (long story) and she nearly crashes it. She's a master practical joker, but he can't figure out where she learned all her tricks since she's an only child. She makes faces at him from the gallery when he testifies in court. For such a skinny thing she holds her alcohol like a pro. Karaoke bars are fun because they like to people watch, but when he finds out she can sing (Jesus can she sing) he likes karaoke bars for an entirely new reason.

He likes to think he's got it all under control. He's not an idiot. He sees the way she looks at him. The way her face lights up when he tells her good job, the way she smiles at him when he buys her lunch, even if it's something cheap from the vendor on the corner. She hangs on his every word. She watches his every move. She bites her lip too often for it to be professional interest.

He's got it under control though. Really.

She has bad days. Makeup doesn't always hide the dark circles under her eyes. She snaps at him, then immediately looks like she's going to burst into tears. He hates that someone told her that her mother wouldn't want this for her. From what he knows of Johanna Beckett, she'd be proud as hell.

Sometimes he goes over the case notes with her, and when he reads the determination in her eyes he falls a little more in love. One morning after one of their Johanna nights (that's what he calls them because he can't bring himself to say Kate nights—that makes him think about other things) he gets called into the Captain's office and asked if Beckett is "detective material".

That's when everything changes. For the briefest moment he considers lying just to keep her, but he can't. He tells the truth: she's the finest cop he's ever trained, and she could be one of the finest detectives the city has ever seen if she's given a chance. The Captain says she'll get her chance: Vice wants her.

Two weeks later she kills someone for the first time, kills someone to save him. Whatever's going on between them that he's pointedly ignored until then suddenly hits its breaking point. He can't ignore it anymore. It's hard to ignore Beckett to begin with, but when her tongue is in your mouth?

Forget about it.

X-X-X-X-X

It's three in the morning, but he can't sleep. He gets in the shower because he feels like the one he took when he got home wasn't enough. All he can think about is the feel of the gun barrel against his temple. He knows that if Beckett hadn't shown up, if she hadn't shot and hit her target, he'd be dead. The look on her face, the cold determination, makes him proud. She's been trained to save lives, and she saved his.

The look on her face after that, the horror that came after it sunk in that she'd taken a life, haunts him. He closes his eyes and lets the spray of the shower pelt the back of his neck, but he can't stop seeing her face. He's proud of her, he's glad the city has a cop like her, but part of him mourns that it had to come to this. She should've never been exposed to death. Not her mother's, not a gang banger's, not anyone's.

He shuts the shower off, dries himself, and pulls on a pair of boxers. He doesn't bother with a shirt. He's cracking open a beer when there's a knock on his door.

He takes a swig of his beer and then swings the door open. When he sees who's on the other side he nearly spits beer all over her.

"Beckett," he chokes out, wiping his mouth.

She's soaked. Her jeans and gray t-shirt are so wet they're dripping, leaving a puddle at her feet in the hallway outside his apartment. Her hair is in a ponytail, slick and smoothed to her head. He stares at the mascara that's run just enough to outline the bottom of her eyes in black before he realizes that her gaze is flitting over his chest, taking in his bare skin.

"You're wet," he says.

She looks up at his eyes. "I walked."

She's wide-eyed, almost like she's terrified. He feels something inside click into place. Maybe it's the adrenaline buzz of realizing that he would've died today if the beautiful woman standing in front of him hadn't saved his life. Maybe not.

It gets out of hand fast. Her skin is soft and her tongue in his mouth makes him see stars on the inside of his eyelids and he's pretty sure she's digging her nails into his biceps so hard she's breaking the skin. He pulls her inside the apartment, kicks the door shut behind her. They stumble through the living room. He pushes forward and she leans back, their mouths still joined as they fall back onto the couch.

X-X-X-X-X

He wakes up the next morning with his arms wrapped around her naked body. Her hair smells good and she's breathing quietly as she sleeps. For a second, he considers waking her up. Round three, shared shower and shared coffee, and then work.

He's more than a little in love with her now. He doesn't wake her up.

Instead, he slides out of bed and gets dressed quickly. He checks her phone before he goes, just to make sure she has an alarm set. When he pulls his front door shut behind him, something inside of him clicks out of place.

He's jumpy at the precinct. He doesn't bother joining any of the conversations happening around him as he changes into his uniform in the locker room. He makes coffee in the break room next, and out of habit he makes one for her. Every time the elevator doors slide open with a soft ding, his chest tightens. Their shift starts soon. She's never late.

And then she's there, stepping off the elevator with a purposeful strut to her step, her eyes scanning the room. He finds it odd that the first day he met her he thought she was timid and emotional. Right now, she's anything but. She's terrifying.

She's beautiful.

He steps out of the break room with two cups of coffee in his hands. Her eyes settle on him, her gaze narrows, and she moves across the room with such furious grace he's suddenly thinking about how graceful she is all the time, how fucking elegant she is even when she's arched beneath him, gasping as she comes.

"Morning kid," he says when she's in earshot, his voice carefully level. He holds the cup out. "Coffee?"

"No."

She spits the word at him, her arms crossed over her chest as she stops in front of him. She's not wearing the clothes she had on last night. She must have gone back to her place to change.

He stands there with his hand out stupidly, and she appraises him. He lets her. She's so different than she was that first day, but there's a vulnerability lurking in her eyes he recognizes. He wants to touch her. He doesn't.

She glances around the bullpen. He follows her lead; no one is paying attention. She leans closer, lowers her voice. "We need to talk. Now."

He lowers his hand. It's the first time she's ever turned down coffee. "Shift starts soon."

Her eyes flash. She opens her mouth and he steels himself, but Captain Nolan pokes his head out of his office and cuts her off.

"Beckett."

She whirls around, a brief flush racing over her cheeks. "Sir," she greets him.

Nolan nods to his office. "A word, please?"

She obeys automatically. Nolan looks at Mike, shoots him a grin. "You too, Royce."

Mike nearly drops the coffee. This is it. This, of all the times, is when Nolan is going to tell Beckett she's being transferred. It was supposed to happen next week, next month, anytime but now, when she's mad at him, when she'll think he only slept with her because…

He moves toward the office. He needs to talk to her, needs to explain, but by the time he gets into the office, Nolan's already started talking.

"Great news," Nolan says, smiling from ear to ear. "But first, I wanted to say you did good yesterday. Saved your partner's life."

Beckett turns her eyes to Mike briefly, and all he can do is stare back. She looks back at Nolan impassively. "Thank you, sir."

"It's icing on the cake." He pauses dramatically. "You're being transferred to Vice."

Beckett doesn't move. She doesn't say anything, doesn't even blink, and after a beat it's obvious Nolan's finding her lack of response anti-climactic.

"Beckett?"

"I don't understand," she says immediately.

"Vice wants you," Nolan says. Mike wants to punch him for talking to her like she's stupid. "It's a chance to make detective. Royce thinks you could be one of the best."

Mike clenches his jaw. Beckett turns her head slowly to look at him. The instant their eyes meet, he knows he's lost her.

The moment only lasts for a second. She presses her lips together and looks away, sends a polite smile in Nolan's direction. "That's great news, sir. Thank you."

Nolan beams. "Of course. I know you've got to write up the report for yesterday, but after that you're no longer a beat cop. You'll report to Vice as soon as IAB clears you."

If it's too abrupt of a change, she doesn't show it. The polite smile is still pasted on her face as she stands. "Yes sir."

She brushes past Mike without looking at him, and he follows her. He follows her across the bullpen, but she still doesn't look at him. He stops next to her by the elevator, watches her press the call button five or six times.

"Beckett," he says.

She turns on her heel and heads for the stairs, ignoring him. He follows. He catches her one flight down, his hand on her wrist.

"Don't," she warns, yanking it out of his grasp.

He half expects her to start walking away again, but she doesn't. She stubbornly refuses to look at him, and he can't think of anything to say. He doesn't do shit like this. He's not good at words.

"You're gonna be a hell of a detective," he finally says.

She looks at him. "What about you?"

He smiles. "You were always going farther than I was. I've known that."

A crease forms between her eyebrows. "Where are we going?"

"You'll get a new partner in Vice."

"And that's it?"

He doesn't know what to say, so he doesn't say anything. Does he want Beckett in his bed again? Hell yes. Does he want to be in a relationship with her? No. He can't give her what she needs, he knows that. She doesn't know it, she's too young to know, and that's why he has to end it before it starts. Because he doesn't want to be like her mother's murder, he doesn't want to be something else that she has to carry around.

She doesn't like his silence, he can see that written all over her face. She steps closer, and he's suddenly thinking about last night, when she woke him up for round two.

"How long have you known about this?"

"Beckett—"

"Kate," she corrects. "You didn't have a problem saying it last night."

That hurts. He sighs. "Damn it, kid—"

"I woke up alone, Mike. In your bed. You snuck out of your own fucking apartment—"

"You don't understand."

She laughs bitterly, and it reverberates through the stairwell. He hates the sound even more when the echo reaches his ears. "Explain it to me," she orders.

"I'm not detective material."

"Who gives a shit?"

"You will. Maybe not now, but you will."

She stares at him. He replays his words in his head. He knows they're not enough, but he's got nothing else. He's barely hanging on to the resolve that he's doing the right thing. She deserves better than a blue uniform and a beat, she deserves a gold shield. She deserves better than him.

"I would've thought you knew me better than that," she finally whispers.

And then she walks away. He doesn't follow this time, and when he catches one last glimpse of her face before she disappears from view, he can't help but think that it might be the last time he ever sees her.

X-X-X-X-X

It's not the last time he sees her.

People think he wants to hear how she's doing. (He does. Sort of.) She's a hit with the guys in Vice. He knew she would be. He tries not to think about her looking at any of them the way she used to look at him. Her bottom lip pulled between her teeth, her eyes sparkling.

He runs into Studebaker, a Vice detective, at O'Reilly's one night. He's drunk enough that Studebaker's declaration of Beckett being a crime solving prodigy who should've been sent to Vice months ago doesn't hurt. Vice loves Beckett, Mike loves Beckett, Mike loves beer, everything is great.

The gray of the next morning is less great, and Mike wonders if she misses him.

Later, he's not surprised when the grapevine reveals that she's made Detective. He spends two days in an internal tug of war, and then he walks past a bookstore and stops short at a display for Richard Castle. Beckett likes Castle. They'd talked about it once, when he'd noticed the books on her coffee table during one of their Johanna nights.

He buys the hardback of the new release and beelines for Vice before he can chicken out. When he gets there, Beckett is holding court. All he can see is her side profile. She's perched on the top of a desk in a tiny, glimmering black dress that makes her legs go on for miles until they stop at a pair of very high black stilettos. There's eight Vice guys around her, and when Mike ducks behind a corner and eavesdrops, he hears her story about busting a high-end prostitution ring. The dress and the excitement in her tone tells him they just made the bust and she tells him (via the eight guys hanging on her every word) that she was undercover.

He peers around the corner like a creep, but he doesn't care. He's never seen her in a dress. She wears it like it was made for her. Maybe it's the trust fund in her.

He leaves before she sees him.

There's a ripple in the department when she gets promoted to Homicide. She's young and pretty and there are cops who don't like her, but for every one who doesn't like her there are eight who do. Mike is always number nine. Detective Howie Ripley from the 13th precinct has a crooked nose that some prick at Manhattan General ER couldn't set correctly to prove it.

He sees her name in the paper one morning. Detective Kate Beckett and Detective Javier Esposito. Esposito. Must be her partner. Probably some punk ass kid from the Bronx. Mike wonders if they're sleeping together. Takes him way more effort than it should to ignore the sick feeling in the pit of his stomach.

When he retires, his department buddies throw a massive party at O'Reilly's. He brings the hardcover of the Castle book he bought ages ago just in case she decides to show up. He keeps an eye on the door all night, but she never arrives. He gets drunk and asks around about her. Someone says she just had a tough case, something about an abducted child they found too late. He's about to drunk dial her, just to see if she's okay, but the rest of the story stops him. FBI agent Will or Bill or something. Worked the abduction case, and then took Beckett home. Mike orders another beer.

In line at the grocery store one day, he happens to glance over the shoulder of the woman in front of him. She's reading a magazine. He double takes and then stares. Beckett smiles at him from a posed photo on the glossy magazine page, looking uncomfortable but incredibly attractive. He buys one of the magazines and reads it on the subway. She's being shadowed by Richard Castle. Muse for his next set of murder mysteries. Go figure.

It's been years. He doesn't think about her every day anymore, but he still thinks about her. He gets messed up in some shit he shouldn't. He tries not to think about what she'd think, tries not to imagine the shocked hurt that would spread over her face if she knew.

And then he hears her voice and smells her perfume and when he stands up and comes face to face with her after years of wondering what it would be like, he can only think two things:

She still looks at him the same way.

He's about to break her heart.

X-X-X-X-X

Maybe sitting in the back of a police cruiser instead of the front is supposed to feel weird. Mike will never know, because something other than weirdness is consuming him, something that feels a lot like anguish.

Or maybe he's just soaking up what's radiating off of Beckett in waves.

It's surreal, watching from the backseat of a cruiser as she runs the scene. She's gotten good at controlling her emotions. Hell of a poker face. She's not the rookie who stood before him all those years ago. She's not a kid. She's a homicide detective. The steely cold of her handcuffs on his wrists won't let him forget that. But he's desperate to see a hint of the woman beneath. He needs to see Kate one last time.

He's proud of her. Compartmentalization is key, and as her training officer he's thrilled. But he's not thinking like a cop right now. He's thinking of her skin beneath his lips, of her laugh from the passenger side of their cruiser, her tears on Johanna nights. He's thinking of Kate, of everything she was and they were and everything they could've been if he'd just…if he hadn't…

He watches her stand impassive and off to the side, directing uniforms and crime scene techs. Watches Castle appear at her side. Watches her poker face shiver but remain. She turns her body unconsciously toward the writer. Castle dips his head toward her, concern on his face. His lips move. A faint smile tugs on her lips. She shakes her head.

And there she is. Kate.

A uniform approaches them. Beckett steps away from Castle, but he keeps his eyes on her. The uniform points at the cruiser, points at Mike. Beckett looks his way.

Their eyes meet. She holds his gaze, her poker face firmly back in place. Detective Beckett, NYPD, staring at a criminal. It hits him suddenly, like blunt force trauma to the back of the skull.

She was right. He should've known her better than that.

She breaks eye contact and nods at the uniform. This time when she walks away, he knows it's the last time.

Sincere thanks to my betas. Special thanks to fialka62 and Cartographical in particular, who made sure I didn't strangle Royce and give up (I wanted to. I wanted to so badly). Thanks also to those of you who review-you are always so wonderful. A longer fic (Castle/Beckett, of course) is coming your way-if you're interested, stay tuned.