AN: This idea came to me while I was chatting with angel-junkie on Facebook today. So this is for you Jess! Thanks for the help with the title suggestions.

Spoilers for 2x24 'A Deadly Game' and 3x11 'Nikki Heat'

A very happy birthday to the magnificent Stana Katic. Without her, Kate Beckett would not be as awesome.

Disclaimer: Nope, still don't own them. I can't wait for the day that I do though.

What Ties Them Together

"Will you marry me?" Castle held up the ring to Kate's face as both Ryan and Esposito looked on in shock. Kate just stood there with her mouth agape. Ryan had been asking the trio advice on how best to propose to Jenny when Rick stole the ring from his hands and showed them how he would do it. What had stunned them all was that they didn't expect for the wave of silence to follow and Kate's response of 'yes'.

A 1000 watt grin appeared on Castle's face as he searched Kate's eyes for any sign that she was pulling his leg and none was found. Processing it all while never taking his eyes off the woman before him he shut the ring box and blindly gave it back to Ryan before digging in his inner coat pocket for a different box.

"I've been carrying this around for weeks trying to figure out the best time to ask you. Were you serious?" Castle was still reeling from the surprise of it all.

"Were you?" Kate countered.

Castle nodded his head fervently, "Kate you are the best thing to ever walk into my life willingly. I would love nothing more than to make you the happiest woman in the world in thanks. That's if you can put up with me and my crazy antics." He smiled his goofy smile at her and she let out a small chuckle before taking the two steps needed so that she could wrap her arms around him. She placed a chaste kiss on his cheek before tracing her finger lightly along his jaw bone.

"Yes, Rick, I was deadly serious. Now can we get back to the murder at hand?"

"Right! Murder…I totally forgot about that. Do you want the ring now or later? I can hold onto it until we're finished."

Kate shook her head, "No, I think I'd like to wear it now." She laid her left hand on top of his as he slid the ring on her finger with his right. It was a simple ring, not gaudy and out there like she had imagined him buying. The diamond was at least three carats with two small sapphires flanking it. The ring itself was platinum with a braided band it was elegant and beautiful all at the same time. Rick brought her hand up to his lips and kissed it just above the ring.

"I love you," he told her quietly, realising that Tweedle-Dee and Tweedle-Dumb were still watching them. Kate just grinned and turned back around to the crime scene at hand; trying to reel in her giddiness over the events of the last few minutes and concentrate on the poor woman that was spiked to the fence.

Their relationship had been kept quiet for months, out of the ever watching eyes of the media and Rick and Kate were relishing the privacy. They kept their dates inconspicuous, never going over the top or to any place where the paparazzi were likely to sniff them out. Both their families and closest friends were kept in the loop as regards to their budding relationship and they were all extremely happy for the couple.

It all started when Rick went away to the Hamptons over that one fateful summer. After a long 'discussion' with Lanie over a few drinks, ok really, they both got completely hammered, and Kate ended up spilling all of her thoughts and feelings about a certain mystery writer.

"Lanie, I just don't know what to do. Stupid Gina is with him and she doesn't appreciate him. They've already divorced once. They won't last, why didn't I say something sooner?" Kate confessed to her best friend as she chugged down her third Sex on the Beach cocktail. The pair was sitting in a quiet bar the night Castle had left and Kate had broken up with Demming. Lanie took another mouthful of her own fruity cocktail before diving headfirst into her friend's problem.

"Ok the main issue that I see here is that you're scared." Kate went to interrupt but Lanie stopped her before she could say anything, "No, don't you try to deny it. You know it's true. You're scared of him rejecting you, but girl, have you seen the way that boy looks at you? When Demming came into the picture, he looked like a kicked puppy. It was sick! He will not reject you."

"But there's too many 'what ifs' Lanie. I can't just go up there and kick Gina out and claim possession of him. I don't own him. What if he's not ready yet? What if he says no? I'll look like a complete idiot and he'll stop following me out of embarrassment and I would have lost the best thing that has ever happened to me," Kate took a breath and whispered, "I can't lose him Lanie."

Lanie thought for a moment and finished off her drink then motioned to the bar tender for another round, she turned back around to Kate and looked directly into her eyes, "Katherine Beckett, I have known you for ten years, listen to me and what I'm going to tell you." Kate took note of the seriousness in her best friend's voice and nodded her head in agreement. "Now, we're going to sit here until last call and drink as much as we can, then we are going to pile into a cab and go back to your apartment. From there we will pack your bag, and knowing our inebriated selves, not much clothing will make it into said bag. That bag will then be locked into the trunk of your car and first thing in the morning, after we have sobered up and caffeinated ourselves you are going to get into your car and drive to Writer Boy's house in the Hamptons and take what is rightfully yours."

In Kate's slightly buzzed state, the idea seemed fantastic, but reason came over her again. "What about Gina? She's going to be there 'keeping on top of him' and his writing."

Lanie patted Kate's hand, "Don't you worry your pretty little head about her, I'll have it all sorted by the time you get there tomorrow afternoon." Again Kate nodded head in forced agreement.

It was just after one o'clock the next morning that the two women stumbled into Kate's apartment. She hadn't been in the place long as it took her forever to find a new one after her old one was blown up. They drunkenly followed Lanie's plan and a duffle bag consisting of a pair of cut-off jeans, flip flops, a couple t-shirts and tank tops as well as a very skimpy black bikini. Added to that were the essentials: makeup, toothbrush and a box of condoms.

By the time that nine o'clock rolled around they had gotten about six hours sleep. Lanie had crashed on the pullout couch and Kate had face planted herself on her bed all the while the world around them was spinning at a blistering pace. In a moment of brief sobriety before she fell asleep, Kate had set her alarm so that she could get up and actually see through Lanie's plan, even though her brain told her it was a bad idea.

After both women were sufficiently caffeinated, Lanie practically had to drag Kate down to her car and make her leave.

"Now you listen to me, I am going to sort out Mr. Castle and he will know that you are on your way. If you don't get to his place within two hours I will find out about it and I will hunt you down and drive you there myself. Have I made myself clear?" It was if Lanie was talking to a child, and a petulant one at that.

Kate sighed, "Crystal."

"Good, now go!" Lanie ordered.

Just under two hours later, Kate pulled up to Castle's beach house driveway, she shut off the engine and just sat there unmoving, not knowing what she should do next. She couldn't turn back, not now. She had come too far to leave. She was so lost in thought that she didn't notice that Castle had come up to her car door and knocked on her window. Kate jumped in surprise and turned her head to look at the offending culprit. Flinging the door open, Kate made her way out of the car.

"Geeze Castle, way to give a girl a heart attack!" she exclaimed. Castle just took a step back from her and chuckled.

"You're too in shape to have a heart attack Beckett."

"That's not the point, I could have shot you."

"I don't see your gun anywhere." He was baiting her.

"Again, not the point." It was working.

He took another tactic, "So, fancy meeting you here."

She rose once again to the bait, "Don't play coy with me Castle, I know Lanie talked to you."

"She did, and? Is there a problem with that?"

Kate crossed her arms in defiance, "No, no problem, I just want to know what she said to you, that's all."

"That's all huh? You drove all the way from the city to ask me what I talked to the good doctor about. Interesting." Castle could see that Beckett was getting flustered and he knew that her hangover was playing a major part in that.

"No, not interesting at all." Kate pressed the palm of her hand to her forehead, the dull ache was now spitting her head in half. "Ugh, Castle, do we have to do this out here?"

Castle recognised her pain and moved to the trunk of her car to remove her duffle bag, where Lanie had told him it was, and then ushered her up the few steps to the front door. "Come on, Beckett let's cure you of your hangover." He led her over to the couch and told her to lay down on it and wait for his return. Castle headed up the stairs to his bathroom to retrieve some Advil. He deposited it, along with a large glass of water, next to her on the coffee table.

"Take that and have a nap, you look like you could use it."

Kate smiled at him weakly, "Thanks Castle."

"I'll wake you up for dinner, feel like anything in particular?" When Kate shook her head, he leant down and placed a soft kiss into her hair, "Sleep well."

Hours later, Kate woke up to the pleasant smell of food being cooked. She glanced down at her wrist to check the time and noticed it had just gone past six o'clock. She had slept over six hours and hadn't stirred once. It was the best sleep that she had in a very long time. Kate stretched and moved off the couch in search for the creator of the aroma. She found the kitchen and sat down at a bar stool that surrounded the high serving bench. Castle's back was towards her and she took in the sight of him cooking. It made her insides melt knowing that he was doing this for her.

"Hey, it smells great." She said it quietly so as to not startle him like he had done to her, although, payback was a bitch. She'd just have to get him another time. Castle turned around to see her wiping the sleep from her eyes and he grinned at her.

"Thanks, I figured that good old fashioned spaghetti bolognaise with garlic bread would be the hangover cure-all."

"Sounds like you're speaking from experience there Castle," she smirked at him.

"Most definitely! Mother loves this; I learnt to cook this at a very early age." That earned him a laugh from the detective.

"You're terrible, Castle. She can't have been that bad. You turned out ok in the end."

Castle stepped back in feigned shock, "Was that a compliment, Beckett?"

"You keep that attitude up and it'll be a very long time before you'll hear another one," she warned him jokingly.

Dinner was a quiet affair, with neither of them willing to broach any subject that may be considered sensitive. It was all a matter of timing for them, it had to be right or else the whole thing would come crashing down at their feet before they could even start anything. The thing being their ever fragile relationship.

"What colour do you think the elephant is?" Castle asked Kate offhandedly as they sat together on the couch after dinner, with neither of them paying attention to the movie playing on the screen in front of them.

"What makes you think it's anything other than grey?"

"You can't answer a question with a question. And besides, I always figured that our relationship was a lot more colourful than plain old boring grey."

A few minutes passed and there was more silence.

Kate was the one to break it, "Green. The elephant is green."

"Green?" Castle was confused; out of all the colours she chose green. He swiveled himself on the couch to face her, "Why?"

"Because green is the colour of jealousy and envy but it's also the color of balance, harmony and growth." She took a breath and continued, "You balance me out and help me grow into a better person. We work together and it's like we're in sync with our thoughts, as scary as that sounds. Also, I'm jealous. I'm jealous of all the women that have been yours and I'm envious of your family."

Castle was stunned at her candid reply, he hadn't expected her to give a response like that.

"And that's why I love her," he mumbled to himself, not realising that he actually said it aloud.

Kate let out a soft gasp, "You what?"

Shit! "I…uh…didn't mean it to come out like that," Rick was in damage control mode after seeing her face full of alarm, "I meant to say that I know how you feel. I know that our relationship, both personal and work, isn't the most conventional. I know you put up with me when you really don't have to. You could have said no and I would have walked away. But Kate, I get jealous too. I want to get rid of the Sorrensons and Demmings of this world because they take you away from me. I want you all to myself Kate." It was Castle's turn to breathe before continuing. "I'm sorry about what happened yesterday at the precinct. I was an idiot for even inviting Gina here and even more of an idiot for not listening to what it was that you really wanted to say."

Kate reached over and placed her palm against his cheek, "It's ok, it took Esposito to tell me what it really was that was bothering you in the first place, and then Lanie forcing me to come here to sort it all out. Who knows what would have happened if they didn't intervene." She took her hand back and placed it into her lap and looked around, "Where is Gina?"

"I sent her packing. When Lanie called and told me that you were coming I informed Gina that I didn't need her help to complete the book and that inspiration would arrive in a few hours."

"I bet she took that well."

"Not really. I don't care, she'll get her book finished before it's due." Kate laughed and crawled up and curled herself into Castle's chest.

"I love you too, Rick," Kate murmured softly into the crook of his neck, "Sorry it took me so long to realise it." Castle placed his finger under her chin and tiled her neck up so that he could look at her.

"Don't you ever apologise, Kate. We're here now and that's all that matters. We're going to move forward together and nothing will ever change that. I've learnt from my two failed marriages that communication is the key to success. I never had that before."

Their faces were creeping ever so slowly together as Rick was talking, when he had finished, Kate closed the gap between them and their lips finally touched. There was an instant spark between them and they let their passion ignite the fire inside them. Hands roamed beneath shirts as their lips danced together. They both let out matching moans of approval and it set their fervor for each other at an all time high, neither of them wanting to let go. Kate was the first one to break away, her whole body flushed with arousal. She had never felt that way before and as sure that if their make-out session was anything to go by, when they got to making love it would be extraordinary.

And it was.

Kate sat at her desk twisting her new ring that adorned her finger and sighed in contentment. Not even the sight of Natalie Rhodes hitting on her fiancé would dampen her spirits today. Kate knew that Richard Castle would be going home to her, every day for the rest of their lives, and she couldn't wait.

Ok that was the longest one shot I have ever written. I hope you all enjoyed reading it as much as I loved writing it. Please R & R as I love to hear all of your comments. All mistakes are my own. I apologise for any typos there may be.