Author's Note: This story takes place a few hours after "To Love and Die in L.A." At the end of the episode, we see Beckett and Castle on a plane back to NYC right around what appears to be sunset in L.A. I'm going to take some creative liberties here and pretend that they didn't get back to the city in the middle of the night. This story starts around, let's say, 11pm, a few hours after they've arrived back in New York.

Also, this story is a song-fic sort of. I've recently fallen in love with the song "Just a Kiss" by Lady Antebellum, and it inspired me to write this story. There may be a few of the song lyrics used as dialogue or thoughts throughout.

Summary: If only…

Disclaimer: The characters of Castle to do not belong to me and neither does the song "Just a Kiss" by Lady Antebellum.

"I've never opened up to anyone
It's so hard to hold back
When I'm holding you in my arms
We don't need to rush this
Let's just take it slow."

"Just a Kiss" by Lady Antebellum

A gold, silk thread of hope shimmered throughout Kate Beckett as she walked the streets of New York City, her hands tucked into the pockets of her light jacket. She had taken a cab from her place towards Richard Castle's loft apartment, but had the cabbie drop her off a few blocks away so she could walk off the rest of her thoughts. She had so much to think about, so many emotions to sift through and sort out. But the words she kept going back to, kept focusing on, were "if only." Royce's letter had gotten to her, had forced her to think about her life and her choices in a different way. His words had brought out all the feelings she tried to keep buried, hidden away, locked in a deep place inside of her.

Well, his words, and others things… like the fact that she had re-opened the door of her hotel room after running from Castle and his honest words and intense gaze. It seemed that in those terrifying thirty seconds she had stayed hidden behind the door to her room, she had made a decision with her heart, instead of her brain; for once. She wondered what would have happened if she had made that decision in five less seconds, and walked out when he was still in the living room.

Kate had been disappointed that he wasn't there anymore, and relieved at the same time. She had felt the two different emotions pulling at her from both sides, in a back and forth tug of war on her heart. She was disappointed, because she wanted… she wanted… something. His reassurance, his words, his love… him. Yet she was relieved because she knew it was awful timing, knew it wasn't right yet, knew they still had obstacles to overcome… namely Josh. It wouldn't have been fair to Castle (or Josh) for her to finally let down those walls she'd built up so carefully, when she was still with someone else.

But now… now hope was threading through her. She had made her choice, made the decision. She still had her fear, quite a lot of it, but she also felt confident. Mostly. There were only so many ways Castle could tell her, with his words and his eyes, that he wanted her - wanted them - before she finally listened.

They were finally on the same page of the book they were writing together.

Nerves fluttered through her as she opened the door to his apartment building and stepped in to the lobby. The closer she got to his apartment, the closer she got to throwing up. She waved politely at the doorman before pushing the button for the elevator. When the doors opened in front of her, she stepped inside, and bit her lip as she pressed the button for his floor. Her foot tapped anxiously against the floor as she gnawed on her lip, trying to calm herself down.

It wasn't working. This was… it. This was… everything. And she was not one hundred percent sure yet that she wasn't going to turn around and run. She wrapped her arms around her stomach and held onto her elbows tightly, trying to hold herself back from running. She breathed in deep, shuttering breaths, willing her heart to slow and her stomach to settle.

The elevator dinged and the doors opened on his floor. She stepped out, took one last, long, deep breath, before walking to his door. She lifted her hand, curled it into a fist, and froze. Okay, one more deep breath, she thought, as she sucked in a lungful of air. As it whooshed out of her mouth, she knocked lightly on the door. And waited. After a few moments, she thought maybe her knock hadn't been hard enough, because no one was answering. She lifted her hand again, and suddenly the door opened in front of her.

But instead of seeing Castle on the other side, she saw his daughter. Kate's heart tripped in her chest, but she managed a smile.

"Hey Alexis."

"Oh, hi, Detective Beckett. Come on in." Alexis stepped back to allow Kate through the door. Kate walked past her and then turned, biting her lip again. She had expected Castle to come bounding out of some other room, but he was nowhere in sight.

"Is your dad home?"

"Yeah. He's in bed, though."

"Oh." Kate glanced at her watch. 11:13pm. "That's…"

She was cut off by Alexis' smile and response. "Early for him. Yeah. He does this sometimes, after a trip or one of your cases."

"He slept the whole way home on the plane, though." Kate frowned.

Alexis only chuckled. "Yeah, he's weird, I know. I think that because he's so wired, so energetic all the time, that sometimes he just has to completely shut down and recharge his batteries."

Kate smiled. "Yeah. That makes sense." And it did. His endless energy always surprised her. She was often jealous of it, wishing she could steal a little of it from him. And she knew that sometimes she did, that sometimes just being near him recharged her. Oh God. It's only been a few hours and you're already turning into a sap, she thought.

Alexis interrupted her thoughts. "Want me to go wake him up? I'm sure if he knew you were here, he'd want to be woken up."

Kate bit the inside of her cheek. "Actually, I'll do it, if that's okay?" She felt awkward, asking his daughter that, but she wanted to do this her way. So if she had to be embarrassed for a minute, then so be it.

Alexis grinned, her eyes twinkling with a humor that reminded Kate of Alexis' father. "Fine by me. I'm going to bed. Goodnight, Kate." She turned and nearly skipped to the stairs.

Alexis' use of her first name didn't slip past Kate. Yet she wasn't surprised by it, either. She was so nervous that surely Alexis must have seen something on her face. She was really going to have to work on her poker face. She was used to wearing it as a cop, but not as a woman.

Kate watched Alexis disappear up the stairs and down the hall. A moment later she heard the sound of a shutting door. So she turned and headed towards Castle's bedroom. When she reached the shut door to his room, she took another deep, steadying breath, before her hand went to the doorknob. She turned it quietly and pushed the door open.

The bath of light from the hallway warred with the moonlight streaming through his windows. It was a little bright altogether, and she wasn't quite ready to wake him up yet, so she shut the door quickly yet quietly behind her. She stood, her back inches from the door, and took yet another deep, steadying breath. He hadn't moved when she entered and she was grateful for it, grateful for a few more seconds of time to prepare herself. Not to guard herself, or her heart, but to find strength to do and say what she needed.

She stepped around the bed, to the side he wasn't occupying. Her shadow fell across his face, so she shifted to the right slightly, so she could still see his face washed in the moonlight. She squared her shoulders for a moment, before easing a hip onto the bed. She lay down next to him, keeping a couple of feet of space between them, which was easy to do on his huge bed. The jostling of her body seemed to ease him out of sleep and she waited, watching as he twitched, then opened his eyes, and then lifted his head a few inches off the pillow to take her in.

"Kate?" His eyes were bleary with sleep.

"It's me," she murmured, keeping her voice low so as not to startle him. And because the mood called for it.

He laid his head back against the pillow and smiled.

"Am I dreaming?" he asked sleepily.

Her lips quirked. "No. I'm really here."

He grinned then, humming a little in his throat. "I'm not sure which is better. The dream I was having about you in that bathing suit, or waking up to find you in my bed."

She lifted an eyebrow and smirked. "Depends on how good the dream was, I suppose."

His smile broke wide on his face and she could see his eyes twinkling in the silvery light. She knew he loved it when she played with him. "Well, in my dream you were chasing after a suspect in your bathing suit. And in reality, you're here with me, so I guess I'll take reality. Although," he trailed off thoughtfully, "In my dreams my intentions don't have to be pure."

She chuckled and rolled onto her back, looking up at the shapes and shadows the moonlight created on the ceiling, a smile still spread softly over her face. For a few minutes, they remained silent, just listening to the sounds of the other breathing.

But finally, finally, he couldn't wait any longer. "So Kate, what brings you to my bed this evening?" His words implied humor, but his voice was serious.

She turned her head to meet his eyes. "I broke up with Josh," she murmured.

"Oh." He swallowed. "I'm sorry."

She dipped her head in acknowledgement. "It's okay, Castle. I… It was a long time coming, you know?"

He nodded. He did know, she had told him as much. They were quiet for a few more minutes, watching each other, communicating in that silent way they had. Until she broke it.

"You know… in the hotel, when I… when I walked away and went into my room…" she trailed off, a question in her voice. He nodded once again. "I came back out."

His eyes slipped shut and he sighed. He had known, known she was going to do that. He had almost felt their connection pulling her back through the door. If only he had waited five more seconds.

"Kate—"

"Wait." She reached over and touched his hand. His eyes opened to meet hers. "I—" She paused and scooted a little closer to him, their bodies only a few inches apart now. "Let me talk for a minute, okay? Let me, let me get this out."

He nodded again. She thread her fingers through his.

"Someone once told me that risking our hearts is the reason we're alive. That we, that we won't want to look back on our lives and wonder, if only." She could see hope springing into his eyes, joy and wonder and that golden thread of hope. "And Castle, I'm tired of wondering."

She squeezed his hand and then leaned forward, ghosting her lips across his for a moment. She stopped to look at him, and he smiled a little, before leaning across that inch of space and taking her lips again. She sank towards him, and he laid his free hand on her hip, holding her close. Just that one touch had a fire burning through her. She wanted to deepen the kiss, wanted to bring them into that fire, but she didn't. Not yet. Not tonight.

She pulled back and smiled softly at him. "I don't want to mess this up." She let her fear shine in her eyes. She was tired of hiding. His hand left her hip to tuck her hair behind her ear.

"And I don't want to push you too far," he murmured. "So, let's just take this slow, okay?"

Kate nodded this time, and pressed her lips to his softly again. Just a kiss, nothing more, just that connection to reassure herself, reassure him. When she pulled back, she smoothed her hand across his cheek, her fingertips brushing against his ear.

"I've never opened up to anyone." Castle's hand rubbed her back. "But you make it so hard to hold back sometimes, Rick." He smiled at the use of his first name, and slipped his hand under the back of her shirt to brush his nails gently over her soft skin. She felt branded by the heat of him. It scared her, but not as much as she had thought it would.

She leaned her head against his chest, hiding her face, and wrapped her arm around his waist. She wanted him to say something, wanted him to be her Castle, the guy who never shut up. She knew that he was probably completely shocked right now, but his silence was forcing words out of her mouth that she wasn't sure she was ready to say. But she said them anyway, because she had made her choice and had decided to take the chance.

"I think you might be the one I've been waiting for my whole life."

He tensed at her words, and then before she knew it, she was lying on her back, his body pressed against hers. His lips stole the breath from her. "Kate, I—You're making it very hard for me not to say things that I know will scare you," he murmured against her neck, as he pressed kisses there.

"I'm sorry, " she said quietly.

He chuckled and lifted his head to look down at her. "You are—you are my hero, Kate. Let's leave it at that."

She grinned at him, and reached up to run her fingers through the soft hair at the nape of his neck. "C'mon, you gotta tell me what that means."

He nuzzled his nose against her cheek for a moment. "I'm just glad you had the courage to come here and say these things. I'm… I didn't want to wonder 'if only' either."

She traced the ridge of his brow line with her thumb. And then Detective Beckett was back. "There has to be some ground rules, you know?"

He smiled and kissed her quickly. "I know, Detective. But let's not talk about them right now. Please?" he asked.

She smiled softly at him. "Okay." Her hands continued tracing his face. "I should go."

His lower lip poked out and made her giggle. So she pinched it gently between her fingers. "But I want you to stay," he whined.

"I know. But I… I think this was… This was perfect. And I think if we give us a little time, that we could have something… real."

"Don't you think three years is enough time?" He asked, but he was smiling at her words.

She grinned back at him. "Maybe. But that was three years of friendship and partnership." She turned on her best sultry-sounding voice. "Consider this time for foreplay."

He groaned and buried his head in her hair. "You're killing me, woman." His voice was muffled against her. She giggled again and ran her hands up and down his back. He lifted his head and pressed his lips to her throat. "Do you have any idea what that giggle does to me?"

She bit her lip, then wiggled her hips under his. He groaned again and she giggled again. Then suddenly, without warning, he was rolling off of her and putting a foot of space between them on the bed. She turned her head to smile at him.

"Just promise me, Kate, promise me, that you aren't going to make me wait three more years," he said, his voice thick with wanting.

She laughed and reached for his hand. "I promise." She raised his hand to her lips and kissed his knuckles gently, before she turned and slipped out of his bed. She walked around to his side and leaned over him, her palms holding her up, over him, her hair tumbling around him. She watched him take a deep breath of her and she smiled. "I'm going, but first I need a kiss goodnight."

His fingers twirled in her hair. "You're such a tease."

She laughed, and then leaned down, capturing his smiling lips with hers. The kiss was hot and wet and full of everything she'd hoped a kiss with him would be. But she forced herself to pull back, to straighten up and step away, even as she trailed her fingers down his arm to give his hand a quick squeeze.

She watched the moonlight dance across his face. "Goodnight, Rick."

"Until tomorrow, Kate." She smiled at him, and then turned, letting herself out, her heart bursting with hope. And she knew Royce was right. Risking her heart had never made her so happy.

She'd finally found that something real.

End Note: Sooo, I hope you liked it! I know that a lot of times, fics about Castle & Beckett getting together aren't usually this light. But the song, paired with my thoughts on Beckett just giving in to it, not fighting it anymore, made it lighter for me. Maybe it was out of character for her, but I like to think that maybe it could be like this, if she would just give in to it. ANYWAY. I know some of the lines were probably a little cheesy, cause I stole them from the song, but all in all, I hope you all liked it! Thanks for reading!