A/N: So, this is my first Castle story, a fact that makes me a bit nervous. I figured I wouldn't try to write anything until season three was over but inspiration comes as she pleases, so here it is.

Takes place say...two years after season three and there are no major spoilers for anything (okay, a teensy bit for 3x17). As always, all the characters belong to Andrew W. Marlowe and/or ABC, only my Muse belongs to me (kinda, but she mostly owns me).

And the song is Blue October feat. Imogen Heap - Congratulations. If you haven't yet, go listen to it.

He watches as the couple takes the dance floor for their first dance as husband and wife. They settle into position and glide effortlessly across the floor, all the while looking at each other, seemingly out of touch with the world around them.

She looks so extraordinary, he thinks wryly and vaguely remembers a time when she wanted to hear that from him, when she needed to believe in him. But another look at the happy couple makes him painfully aware of the fact that she possibly, probably, maybe, most definitely was not his to begin with.

Their relationship was not easy, he knows that but he cannot not believe that there was a time she was willing to give him a chance, to make her happiness by his side. It took some effort, some convincing and a particularly laughter-filled trip to the beach but she told him she wanted to try and it made his heart ache in a very pleasurable way.

Now he knows they were deceiving each other. Seemingly different but they were cut from the same tree and he thinks if he had had a little more time, more persuasion on his side, more of something undefinable, he would've broken through to her. But the seams holding the canvas of their relationship were fragile to begin with and it was going to tear open eventually.

The sound of laughter is carried towards him and he sees the moment he dips her and then pulls back to him, like he's always meant to do so and the smile she gives in return is one of absolute radiance.

It is in stark contrast with the last time he saw her, when her face was filled with doubt and fear and she explained how they could never work, how his kind of life would always get in the way and no matter his words, she refused to take them that time. He still remembers the heartbreak and the consideration in her eyes when she realized how much it hurt him but still refused to take it back even when he pleaded.

The extent of that is evident in the wide-eyed blonde sitting next to him whom he married after a whimsical romance just six months after his heart had been crushed. The woman he could - and should - call his wife was so unaware of everything and when his voice wavered a little as he told her they were expected at this wedding, she only smiled and went shopping for a dress.

He watches them for a while, the little smiles and knows that he has to talk to her. He stands up just as another song breaks in and makes his way towards the couple, trying to put on his best poker face as he taps on her husband's shoulder.

"I was wondering if I could steal the bride for a moment? I've been dying to dance with her," and accompanies it with a smile in their direction.

He's not sure what he expected from the man but the look of commiseration and understanding of things and feelings unresolved is not it. He releases his wife with a soft kiss to her cheek and leaves. She turns forward and they settle into position but he can see the fear of something in her eyes.

"You look beautiful, Kate. Congratulations."

She gives him a wary look but manages a smile. "Thanks."

I came to see the light in my best friend

You seemed as happy as you'd ever been

My chance of being open was broken

And now you're Mrs. Him.

My words they don't come out right

But I'll try to say I'm happy for you

"So you really did it. I am happy, you deserve this, you both do." He tries his best to keep any hint of bitterness or accusation out of his voice but she is not a detective for nothing and frowns a little at the underlying tone.

So he assures her. "I know you're afraid I will do or say something but I will be on my best behavior, I owe you that much."

"You don't owe me anything and you know that." Her voice is confident and a bit sad.

They sway for a bit, his mind once again going back into the past, taking bits and pieces of her, of them and trying to figure out things to say.

"I should've known I didn't have a chance. I was too late and he became your one and done and no matter what I said, you had made up your mind. You're quite determined that way." She stiffens in his arms when he mentions the one-and-done, something that brings back memories for her as well, he supposes, of things he was never supposed to even know.

"I don't think I knew what I was doing. I am sorry I had to hurt you but being with you would've hurt us both and everyone around us even more. There was more to this equation than just you and me and you know that."

She is right, as always but it doesn't mean he was willing to let her go when it was ending. "I thought I had you, I managed to convince myself I had a chance after the bomb, you know." Once again he's bringing up things she doesn't want to remember and he knows but more than that, he needs to know what happened to them.

She gives him another look but this time it is softer, filled with regret. "I know. I was certain of that as well but we were just disillusioned by everything that happened around us that we forgot to check what was inside us."

It is the truth and it hits him with a pang so the anger and frustration inside him wells up and before he can stop himself, the words are out of his mouth. "You know, they do say one should never marry his muse, it will only ruin the illusion."

He's hurt her now but it's only a brief flicker in her eyes until she steps out of the dance – which has ended anyway – and gives him a final look, sad yet caring. "Don't become bitter, Josh."

And just like that, Kate Castle walks away from him, over the floor to her husband and Josh knows he never really stood a chance, he never was her one-and-done.

A/N: Now, a show of hands please - who thought Castle was the one in anguish? The story came to be in my head with Kate marrying Josh when I listened to the song but my Muse decided I can't write a sad Castle, so this happened instead.

Thank you, come again.