Accept No Substitutions

a co-authored Nikki Heat AU with jstar1382

Castle stared.

Natalie Rhodes was dressed like Beckett.

No, Natalie was dressed up like Nikki Heat who was inspired by Beckett…

The character and actress became a blur in his head as they stepped into the elevator. Reality versus fantasy was a jumbled mess playing out before him.

Natalie-Heat-Beckett leaned in. "I need to feel that heat…"

Before he realized what was happening, she was on him, mouth molding against his. Castle was shocked into participating, his body moving before his mind fully caught up to his actions.

"Wa - wait, Natalie." He nudged her back, creating a safe distance between him and the actress, who seemed all too willing to act out of whatever meta fantasy his mind could conjure up. This was a bad idea. At least his hormone-sludged brain was able to conclude that fact quickly enough to allow him to sidestep as the Beckett wannabe leaned in for another kiss. "No."

Her jaw dropped. Her reaction said he might be the only person that had ever had the nerve to utter that word to her. The air was thick, her body still in too close a proximity to his. He was trying to be fair, but he was a hot-blooded male.

She blinked. "No?"

"No."

"You know who I am, right?" she scoffed, narrowing her eyes. "I mean, I need to research the role and you - this relationship is definitely part of the Nikki mystique." She tried to move closer, like a huntress on the prowl, relentless.

The four walls of the elevator car were closing in on him. He dodged her assault and jumped to the opposite side. "I get that, trust me I get that, but I can't do that to her."

"To your character?"

"No, not Nikki. I can't do that to Beckett. It's complicated and this," he said, motioning towards her body, noting her near identical appearance to his partner. "This, as great as I'm sure it would be, would just complicate things further."

Natalie rolled her eyes with a half-hearted laugh, looking entirely too similar to Beckett in all of her mannerisms for his health.

She smoothed her blouse that had wrinkled from her kiss. "I don't get it, Rick. It's just sex."

The door slid open with a ding, a welcome sound, and a sigh of relief released from his lungs.

"You're right." He offered her a parting smile, stepping off of the elevator into the lobby. "You don't get it. Goodnight, Natalie."

(...)

The idea that Natalie Rhodes was well on her way to doing exactly what Beckett had feared - steal her boyfriend and kill her in her sleep - had Kate not so much horrified as heartsick.

Castle had dropped the wig box. As if his fingers had been nerveless, as if Natalie's kiss had been so great, he hadn't been able to control himself. As if-

Why was Kate obsessing? What did she care that Natalie Rhodes was doing research?

But she did. God. It was mortifying how much she cared.

Beckett sat back in her chair and allowed herself another minute to wallow in misery, her eyes following the indicator light over the elevator as it descended to the lobby. She allowed herself one minute, and one minute only, of swallowing back the tightness in her throat, of replaying the scene in her mind (how stunned he had looked, how Natalie had knocked him off his socks, finally shut him up, and it was so hard to shut him up), and then Kate sealed it off.

Closed it down. Shut the door.

Beckett turned back to the murder board, the elements of the match-maker's life neatly plotted out on the timeline, all the salient points and pertinent details, as well as a few that weren't so vital but which might prove decisive at some later date.

Never knew with a murder. Like she'd said, it was a numbers game; she would throw things up there until something shook out.

This was her element, this was where she excelled, and it was by doing this very thing: sit at her desk and stare at the board until patterns emerged. Put in the time. Do the work.

Eventually it would pay off.

She had to believe that.

(...)

Of course, easier said than done.

Beckett's concentration was shot after all that. She had tried; she had stubbornly sat before the board and told herself that none of it mattered, but it wasn't true at all.

It mattered.

And she hated that it mattered, and she hated him for mattering, and Natalie Rhodes for seeing that it mattered and so attacking Castle on the elevator by using Kate Beckett's own appearance and body language and mannerisms and everything.

It was having Beckett without having to have Beckett, and Kate wasn't at all okay with that.

A stand-in.

A substitute.

(Cheap imitation.)

So she quit.

Beckett logged off her computer, thumbed the monitor dark, and stood up. She arranged her phone in her back pocket, pulled on her jacket, checked her holstered weapon by habit. The precinct wasn't dark by any means, but it had the air of being abandoned, as if even third shift had given up the watch.

She wasn't on call. Most of her queries wouldn't come back until tomorrow morning. She had nothing else to do here.

When she strode through the bullpen, she had a moment's hesitation at the hallway where her path divided. The elevator was one way, the stairs the other, and still the image of Natalie Rhodes pressing Rick Castle against the side of the car stuck with her.

Burned in her brain. (She tried to tell herself that was a good line for tomorrow morning when Castle walked in, jauntily, with coffee. She would be snarky and smirking, poking fun of his playboy ways, of having crossed off Ryan's Freebie Five list for himself, of anything other than how her guts rolled and her feelings were hurt.)

She headed for the stairs.

She just couldn't do the elevator right now.

Maybe not for a while.

(...)

Rick Castle sat in his car, unable to start the ignition, his mind reeling with the events of the day. His hands gripped the soft leather of his steering wheel, knuckles blanching white. After the confusing summer and the ill-fated reunion with Gina, he had thought he finally had his feelings for Beckett straight in his mind.

She wasn't interested in him and it was okay. He would rather be in her life as her partner, than not in her life at all.

Partners and best friends.

It was fine.

At least that was what he had convinced himself of, but he wasn't fooling anyone - most of all he wasn't fooling himself. Natalie Rhodes nearly mauling him in the elevator had cemented one thing and one thing only in his mind. He couldn't settle for a cheap imitation when all that his body and soul craved was the real thing.

Kate Beckett was irreplaceable. She was a walking contradiction, both hard and soft, dark and light. Perfectly imperfect, she was all he'd ever wanted.

How could he ever settle for a generic substitute when the original graced him with her presence every day?

He closed his eyes for a moment, letting out a long breath, hopelessness washing over him. He had basically given up since she'd turned down his invitation to the Hamptons, told himself to move on, stop bothering her.

But that meant the newly single Beckett had no idea he wanted her still.

On top of his silence on the issue, he could admit he'd been tongue-tied over Natalie dressing up like Nikki. Beckett wasn't blind. She had to have seen his schoolboy reaction. He had practically drooled over the actress. But it was all superficial with Natalie, not like with Beckett.

There was nothing superficial about his feelings for her.

God, what if he'd blown it today? What if the fact that he couldn't momentarily control his baser instincts had ruined his chance with Beckett? He'd said nothing in months and he'd done the exact opposite of what he truly felt. Great.

He was an idiot.

With a sigh, Castle opened his eyes, blinking the haze away. And noticed Beckett hurrying from the building in search of her car. It didn't take a novelist to see that she was visibly upset. He could guess why. To hell with subtext and dancing around the issues that hung over them, he was done with the games, he was done with silence.

Reaching for the handle, he shoved open his door and jumped out, only to have the rebound smash it against his knee. His rather girly yelp must have caught her attention, because her head jerked toward his, a startled noise from her lips.

"Castle? Wha - what are you doing here?" Her face was flushed.

"I was -" He rubbed the sharp pain of his knee, tried to meet her eyes, a smile forming on his lips. "I was looking for you. Can we go somewhere to talk?"

(...)