She could kick herself. All these years she'd been waiting for the perfect guy, her one and done, who would sweep her off her feet, and he's been right there. He's had her back for four years, there for her no matter what, and she didn't consider it. At least not seriously.

She didn't know what she was expecting when she showed up at his door, soaking wet. She didn't want to imagine what she would have done if he pushed her away, like she deserved. "I just want you." Is that the best she could come up with? His voice echoed in her mind, reminding her that he was unafraid to share his feelings. Why couldn't she do the same?

Their second round was not over as quickly as the first. They took the time, getting to know each other's bodies, learning what made the other one cry out or made their eyes roll back into their head. They whispered things that the other needed to hear. Castle's "I love you" echoed in her mind, and her "I need you" just seemed to pale in comparison. But it seemed like enough for him, as he kissed her deeper each time that she said it.

It was as he held her close after the round was over, their hearts seeming to beat as one, when he asked her the question she dreaded. "Why today? What changed?"

"Earlier today, when we argued, you said it again." She spoke softly, afraid to shatter this illusion she must be under, afraid to wake up from this marvelous dream. "You said that you love me, and I couldn't ignore it this time." His arm stiffened around her as she spoke, and she worried she had said the wrong thing. "I didn't want to ignore it last time either, I just thought it would be easier. I had to work on me, and if you knew that I heard what you said, it would just be added pressure on me to get to a place where I could be with you faster. Or I would have done this too soon and it would have crashed and burned. I never wanted to reject you, Castle, never." His arm relaxed, and started trailing feather light up and down her spine again, goosebumps popping up all over her naked body as he held her close. "The last few weeks I started to recognize something. I think I'm in love with you, and I'm terrified."

"Why?" His voice seemed hurt, like he didn't understand. "I won't hurt you, Kate."

She sighed, her voice hitching with unshed tears. "I'm not afraid of you, I'm afraid of me. I'm afraid I'll self-destruct and mess up everything we have. I'm afraid I'll never be good enough for you. I'm afraid that something else will come along and you won't want me anymore."

His hand stopped it's movements, wrapping around her waist and tugging her closer still, closer than she ever thought they could get. "I don't want anyone else, Kate. It's always been you." They were silent for a long time then, his breath slowing, and his heartbeat loud in her ear. She was about to drift off when she heard him again. "Marry me?"

She stiffened against him, not sure how to respond. Was he serious? She could hear his heartbeat pick up the pace, beating faster as he awaited her answer. He started to backtrack. "Nevermind, I'm being stupid. Forget I said anything."

"No!" Her voice was loud in his room. Her heart was racing as she leaned back to look at him. "It's not stupid. You've known about your feelings for at least a year now, probably longer. You love me, I get it." She paused, offering him a small but brilliant smile, trying to reassure him. Her hand cupped his cheek. "I'm still coming to grips with my feelings. I'm just starting to realize what loving you means, and how to do that. I need that time that you've already had." Her hand dropped from his face to his chest. "I love you. I think you're my one and done. Time is not going to change that. Can you give me some time to learn how to love you completely, and then try that again?"

His relieved grin lit up the room, calming her nerves. "You love me? Even though it's terrifying, you love me?"

She chuckled. "It's terrifying and exhilarating all at once, but yes, I love you."

"Then I can wait. But you better say 'yes' next time, Kate."

She laid her head back on his chest as she snuggled in closer, her eyes closing in preparation of sleep. "I will, I promise."

A year later, surrounded by their family and friends, her resounding yes made the room cheer.

A/N: The two sentences that inspired this were sent to me on tumblr.

I think I'm in love with you and I'm terrified.

Marry me?