Because he broke her fucking vase. And it was her favourite! Oney based loosely on themes from 5x17 and earlier in season 5. It's a fight. It has a happy ending. Slightly OOC, someone requested this kind of thing so feel free to skip it if that's not what you like.

FIGHT

"It's not just the vase, Castle," Kate sighed.

"Varse. Not Vayse."

"Do you always have to correct everything? Can't there just be two ways to say it?"

"Sorry! I just... writer's habit."

"Whatever. Fine. You're a writer. You're famous. You're a nine year old on a sugar rush and you can get away with it because you're cute and charming and ruggedly handsome and- ugh!" Kate ended in a scream of frustration.

"Look, I said I was sorry! Why can't you accept that?"

"Because sorry isn't a magic word, Castle! It doesn't just fix everything!"

"Well what else is the matter, then?" His voice softened. "Are you.. Look, hon, is it your time of the month?"

"Fuck you!" Kate screamed. "No! That is such a pathetic guy thing to do. Blame hormones, blame 'women things'. It's not the fucking hormones, Ricky, it's YOU! YOU are why I'm angry!"

"And what the hell am I supposed to have done?!" They were both yelling now, standing opposite each other in Rick's apartment.

"Nothing! Everything! I don't... I'm putting my heart and soul into this relationship but you're just the same kid you've always been. And the fact that you broke my favourite vase while playing video games in my apartment... You behave like a teenager! And I know NOTHING about you!"

"We're still on that? Jesus, Kate, didn't we talk? Didn't you agree that you KNOW me?"

"Maybe I was WRONG! Because today I don't know shit about you – and from what you're saying, you don't know shit about me!"

"Kate! You're being unfair! I... What do you want to know?"

"Nothing! I don't want to have to interrogate you to get even a snippet of information about you! And you... You just make jokes! You avoid everything. You mess around, and it's cute, but... I want us to be MORE."

"Well maybe you should go somewhere else! Or maybe you should just wait, like I did for FOUR YEARS while you fucked around with nowhere guys in nowhere relationships because you couldn't face being honest with yourself!"

Kate gritted her teeth. "That was low," she muttered. Rick was still shouting.

"You deserve it. So I broke your vase. So what? If we're not more than that, what's the point?"

Kate picked up the vase off his piano, suddenly seeing red. She hurled it at him; it smacked against the wall and shattered.

"There!" she yelled. "Now we're even!"

Rick gaped at her. "You just broke my vase!" he shouted.

"I know! See how you fucking like it! Oh, wait, it wasn't me. It was the wind, you know, blowing in from the window."

"Kate, come on!"

"Come on and what? Forgive you? I don't give a shit. It's a fucking vase. Just like that one was. I just... You lied about it! You have to be grown up. Don't hide me in your closet, don't lie about the vase, don't end up on your couch with some bikini wearing slut from TV! Be a fucking adult, Rick, because I want to be with one!"

"And you're so damn perfect, are you?"

"I think I do better than you! I've given so much, but you can still be such an idiot, such a child!"

Tears were streaming down her cheeks as she screamed at him, not just pouring but throwing out her heart.

"Fine! I love you! That is all there is. You're fucking everything."

"Not good enough!" she shouted. "It's like sorry. I love you isn't some kind of fix it phrase you can pull out when you piss me off. You have to do better than that!"

"What if I can't? What if I'm not perfect? I don't save lives, I'm not a real cop, I don't have a six pack and I'm sometimes an idiot! So what?"

"So... Care more! Don't just act like you're dumb and there's nothing you can do about it! Fix things. Do BETTER! WANT TO DO BETTER!"

"Kate Beckett, now apparently queen of all relationships! You know less than I do!"

"Mister two failed marriages! I'm beginning to see why!"

"Now who's shooting low?"

"Sometimes you make me so angry, Rick, so angry I want to-"

"WHAT? WHAT DO YOU WANT TO DO? LEAVE? DO IT!"

"DON'T EVEN TEMPT ME!"

"IF YOU WANT TO GO YOU SHOULD. OR I WILL!"

"SO YOU DON'T EVEN WANT TO TRY? YOU'D RATHER I JUST WALKED AWAY?"

"I would NOW. You started a fight, but I DON'T WANT ONE. I HAVE SPENT FOUR YEARS OF MY LIFE WAITING TO BE WITH YOU, WISHING YOU WOULD SEE THAT I'M RIGHT HERE AND I'M READY AND I LOVE YOU... AND NOW THAT WE ARE TOGETHER ALL YOU WANT TO DO IS PICK HOLES IN THIS. It might not be perfect but I thought it was worth something to you!"

"I thought so too! But you just... I can't believe you want me to leave. But you know what? FINE!" She marched towards the door and stormed through it, slamming it behind her. Rick stared after her, still fuming.

And then his heart stopped. Was that the end? Had he just ended it? His phone was out before the thought had even finished.

"WHAT THE FUCK NOW?" she shouted down the phone.

"Hey! Don't you shout at me. And don't you walk out on this."

"Make your fucking mind up!" she yelled, marching back through the door and slamming her phone down on the counter. "I am only back because I AM NOT NEARLY DONE YELLING AT YOU!"

"WELL I MIGHT HAVE SOME MORE YELLING IN ME TOO!"

"GOOD!"

"GOOD!"

They glared at each other, both full of fire.

"I DO tell you things!" Rick shouted suddenly. "You know EVERYTHING about my marriages, about my daughter, about my mother, about my books... You know I had an awful time at school. You know I protected myself with humour. You know I had no father; that my mother was erratic and I was alone a lot as a child... What more do you want?"

Kate bit her lip, still crying, still wishing for something but she didn't know what. Just...

"I want... I don't even know! Why do I have to know? You could be spontaneous, you could take control and not just ask me what to do at EVERY SINGLE HICCUP!"

"SO NOW YOU WANT ME TO TAKE CONTROL? Who are you and what have you done with my girlfriend? Kate, you're the biggest control freak in New York!"

"Well someone has to be the grown up!"

"Maybe if you gave me a chance I might surprise you!"

"Maybe if you gave being grown up a shot I might believe you! And that's what I mean. I SHOULDN'T HAVE TO GIVE YOU CHANCES! You should TAKE them. Be a fucking MAN, Rick!"

Rick took a step towards her and suddenly lowered his voice, staring at his tear-stained girlfriend with messed up hair and piercing eyes.

"You want me to be a man?" he asked quietly. She just stared, so he grabbed her and crushed her mouth to his.

Kate was desperate to resist but she felt herself melt into him, unable to pull away for almost a minute. When she finally did push him off her he had that stupid grin on his face.

"And that, Detective Beckett, is why you are with me."

She shuddered. "Fuck you," she whispered.

"If you like," he said, reaching out to touch her cheek. She swatted his hand away angrily.

"You're just... evading the point again!" she shouted, but her heart wasn't really in it.

"And what is the point, exactly?" he asked, mildly amused but with a hint of threat. It was a new voice, something she hadn't heard from him before. It was... dangerous. Hard. Strong. And there was absolutely nothing childish about it.

Kate narrowed her eyes. "You broke my fucking vase," she muttered. Rick took hold of her arms, pinning them to her sides.

"And you broke my fucking vase," he said, his voice icy and on fire at the same time. He kissed her and this time she didn't even have the option of pushing him away – not that she wanted to. He kept his eyes open; they cut into hers as he punished her mouth with his, teasing her lips with his teeth, pressing his tongue deep inside her. She let out a little moan and he stopped kissing her so he could speak.

"Is this what you meant by taking control?" he asked, as if daring her to try to fight with him again. She suddenly felt weak at the knees; she wanted him. She wanted him to take her. She smiled. He chuckled.

"No more fighting," he whispered gently as he kissed her neck. "And I am sorry."

"No more fighting," she repeated. "And... that's okay."

"Want to know what number one was on that 'stupid bucket list'?" he asked as he unbuttoned her blouse. She gasped as his hands found their way under it, and then to other places.

"Go on then," she breathed. "What was it?"

He paused, sliding her blouse off her shoulders and tugging his own shirt over his head. Then he cupped her face in his hands and kissed her again.

"Be with Kate," he said simply.

So... got that out of my system. Please leave a comment! Thanks for reading.