Richard Castle had adopted a new philosophy as of late. It seemed that last few months were opposite day for the famous mystery writer, well when it came to NYPD Detective Kate Beckett at least.

He just knew he didn't want to screw this up, it meant too much. After almost four years of following around the sometimes too serious and prickly Kate Beckett, the duo decided to dive in and test out the relationship waters.

"I would be there for him and he would be there for me and we could just dive in together." He remembered Kate telling him last year when they were locked up together after they believed they had been exposed to radiation.

And dive in they did. For when that wall Kate had placed around her heart began to crack it quickly tumbled down around her. Kate had told him once that the "wall" couldn't come down until after she solved her mother's case. Although Johanna Beckett's murder case still remained unresolved, the feelings between the mystery writer and the detective had definitely been resolved.

It happened a couple of weeks after Castle and his mother Martha had been held hostage in the bank where Martha was seeking a loan for her acting school. Castle had seen subtle changes with Beckett, she smiled more, joked more and he enjoyed seeing her open up. She broke wide open after the bank ordeal, and he was shocked the first time she stroked his shoulder, in the precinct, and even took his hand once or twice.

One Saturday evening, when Alexis and Martha were out, Castle had settled in his office to write. It didn't go unnoticed that he was sitting home alone on a weekend night, and his mother's words kept bouncing around his head, about how he had become a shut-in.

A knock on the door halted his attempt to complete the scene between Nikki Heat and Jameson Rook as they were headed to the bedroom. Castle admitted to himself whenever he wrote the scenes between Nikki and Rook, he sometimes imagined himself with Beckett. How could he not?

He shuffled to the door and opened it, shocked to see Kate Beckett on the other side. She was dressed in jeans and a white T-shirt, her hair pulled back in a ponytail. She looked relaxed, casual and flat-out hot as hell.

"Hey, Castle, can I come in?" Kate Beckett asked with a hint of hesitance.

No need to hesitate when you are looking like that in my doorway, Castle thought.

He opened the door wider and held out his arm, allowing her access to his loft. And my bed, the thought popped in his head. Easy Castle, his internal monologue warned.

"What's up," Castle asked. He shut the door behind him and watched Kate walk over to the living room area. "Please," he offered up, gesturing toward the couch.

Kate sat down at the edge, near the arm of the couch. Castle settled down on the other side.

"I have been thinking a lot about what happened at the bank," Beckett began. She brushed her long brown wavy locks from her face. She then laced her fingers together laying them on her lap. "About what I would have done if something happened to you?"

"Like I told Alexis, there is no need to dwell on that," Castle offered up.

"But I can't stop myself," Beckett said back to him. She scooted across the couch and placed her hand on his knee. "And I have come to a conclusion."

"And that is," Castle all but croaked out as her hand slid up to his thigh.

"Walls be damned," Kate Beckett said in barely a whisper as she leaned in and kissed him. And it wasn't just a kiss, it was a branding. A searing of the soul, pent up frustration, I am tired of waiting kiss.

And the kiss was just the prelude to what happened next. There was discarded clothing, mussed hair and rumpled sheets. The aftermath wasn't awkward or uncomfortable, the morning was full of smiles, laughter and why hadn't we done this sooner.

It wasn't all sexual bliss and roses. This was Kate Beckett and Richard Castle after all. After the wall was down there were heated arguments over a case, over where to eat, when to tell their friends they were dating and what to tell Alexis and Martha.

The biggest blow-up came when Kate and Rick appeared in the page six gossip column, stating that Rick Castle had finally bagged his muse. Beckett was fuming, Castle was secretly beaming and the whole precinct walked on egg shells for two days.

It finally blew over, as these things do, and it was back to lingering looks, coffee breaks and dinners at home for Castle and Beckett.

Now came the hard part. Burning a hole in his trousers was a black box from Tiffany's. The single solitaire diamond was simple and tasteful. Yet another opposite day move from Castle. When he proposed to his first two ex-wives, the rings were flashy and loud and weighed heavy in his pocket.

This ring weighed heavy for another reason. Because for once in his life, Rick Castle was unsure; unsure about what Kate Beckett would say and unsure of where to ask her.

He had told Kevin Ryan once that a proposal should be big and flashy. After all, that was what he had done for his other proposals. But a proposal in a hot air balloon, or a trip in a yacht around the New York harbor, or even on the beach at his estate in the Hamptons wouldn't feel right for Kate Beckett.

It finally hit him when he climbed in the car with Beckett as they were leaving a crime scene. The late afternoon sun was beaming through the car window and the stench of the city streets were wafting through the car. This would be a huge warning bell to most people, don't ask her here. But for Richard Castle, he knew there was no other place.

Richard Castle had met Detective Kate Beckett during a murder investigation and it seemed only fitting they get engaged during one.

"Hey Kate," Castle began.

"Listen Castle, we are not stopping for doughnuts on the way back to the precinct," Beckett said as she jammed the key in the ignition. "I told you we are cooking at home tonight and I want you to eat it."

Wow, Castle thought; that sounded very domestic of Beckett. It was a sign.

"Um, I wasn't going to ask that," Castle said. He reached in his pocket and grasped the ring box. "I do, however, have another question." He pulled the box out of his pocket and popped it open.

"Kate Beckett, I think I have loved you since the first moment I saw you," Castle began. "You are my partner, my best friend and my equal in every way. I love you. Will you marry me?"

Beckett's mouth formed a perfect "O" as she stared at him. She couldn't believe Richard Castle was asking her to marry him at a murder scene. The man was crazy, childish, impetuous and infuriating. He was also the man she loved more then she could ever imagine.

"Really, Castle, you ask me to marry you at a crime scene?" Beckett shook her head.

Castle swallowed hard, waiting for her to say no. She was pissed. She was going to say no.

"What took you so long," Kate Beckett asked. She leaned in and kissed him soundly. As she broke from his embrace she leaned in to his ear and whispered, "That is a yes, by the way."

Castle took the ring from the box, slipped it on her left hand ring finger and captured her for another heat-filled kiss.

Opposite day wins again, Castle thought as he kissed her again.