A/N: This little plot bunny wormed its way in my mind from one of the season 4 bloopers and wouldn't go away. Set during 4x21, Headhunters. Two-shot ('cause it got a bit long for a one-shot). Rated T for a few scattered swears.

"I know not whether I do not too much indulge the vain longings of affection; but I hope they intenerate my heart..." - James Boswell, The Life of Samuel Johnson, 1791

Intenerate My Heart

"What do you want to do?"

"I want to fuck his brains out."

The words were out of Kate's mouth before she could stop them, and while they surprised her, Dr. Burke didn't seem fazed at all. He just looked at her with that expression, the one that would be neutral to the untrained eye. But Beckett could see the hint of a smile, the lone giveaway that he was two steps ahead of her and knew exactly what her next move would be.

So, needless to say, he didn't look at all surprised at her admission. In fact, he almost looked amused.

"Is that all you want to do?"

Kate sighed and slid down into the armchair. "No. I don't just want sex. That would have happened a long time ago if I did. I want – more." She made eye contact with him again. "I'm a better person when I'm around him. He makes me want to be the woman he deserves, to be whole."

"But you're not whole. He's not whole." Dr. Burke folded his hands in his lap, pen and paper long abandoned. "Kate, you need to understand that nobody is a complete, whole, put-together person. Everyone has issues. In Castle, you've found someone whose strengths balance out your weaknesses, and vice versa. He helps hold you together."

"Like the sniper case."

Burke nodded. "The sniper, the bank robbery. Let me ask you: if Castle hadn't been a hostage, would you have gone to the bank that day?"

Kate shook her head. "Of course not. It wasn't my division, my jurisdiction – oh." She paused. "I went there because I needed to get him out."

"Because he's your partner? Your friend?"

"Yes."

"Really?"

Shit. "No." Kate swiped at the tears that had begun to fall. "I love him," she whispered, barely audible. "I love him with every fiber in my being." She chuckled. "God, that's sappy."

Burke smiled then. "Maybe a little. But I'm relatively sure you should be telling that to someone else."

"Katherine, darling, what a surprise!" Martha exclaimed, opening the door with her usual flourish.

Kate wrung her hands in front of her and looked past Martha, trying to see more of the loft. "Hi Martha. Um, is Rick here?"

Martha stepped to the side, motioning for Kate to enter. "No, he's off with that other detective. But, since you're here, I want to talk to you."

"Sure, of course." They sat on the couch. "What's going on?"

"I'm worried, Katherine," Martha said once they were settled. "He hasn't acted like this in years, with that weekend trip to Vegas, then coming home with that girl—"

"The flight attendant."

"And now he's running around with this other detective, what's his name?"

"Slaughter."

Martha shuddered. "What an awful name. This man, he seems dangerous. Has Richard said anything to you about it?"

"He just said he needed something different, something new." Kate almost missed Martha's subtle nod, the small lift of the corner of her mouth. "Martha, why? What did he say to you?"

Martha took Kate's hands in hers and squeezed. "Oh darling, you two really need to work on your communication. Talk to each other."

"I tried. I asked if everything was okay, he said he's never been better. I tried last week, but he shut me down. I don't know what to do."

"Do you care about him?"

"Of course."

"Does he know this?"

Kate shrugged. "Well, yeah. I would assume. I mean, I've never come right out and said so, but he knows I do."

Martha cocked an eyebrow. "If you've never told him, how would he know?"

"Well, he hasn't said anything either!"

"Hasn't he?"

Kate opened her mouth to protest but nothing came out, the pieces finally clicking together.

He knew.

She didn't know how, or when, but he knew that she'd heard him that day in the cemetery. And that she'd lied to him about it.

The bombing case. He'd heard her.

Shit.

She groaned and leaned her elbows on her knees, pressing her hands to her face. Finally, after a few long seconds, she looked at Martha again, trying to ignore the look of satisfaction on her face. "Am I too late?"

"I certainly hope not. But you need to get him back."

She tried to call him for three days after his case with Slaughter was over. The first two days he answered the phone with a curt "Dead body?" and she couldn't lie to him anymore so she said no, to which he promptly hung up without another word. Her call on the third day went straight to voicemail.

On day four she enlisted Martha's help. They'd had a long talk in the loft, and Martha had confessed that at first she was just as upset as Castle that Kate had lied about hearing his declaration of love. But she understood why Kate had done it, and now wanted Kate and her son to make up if only to get him back to normal.

Even if Kate knew normal would never be the same.

So Martha made herself scarce on Kate's next day off; she showed up at the building with coffee and bagels just as Martha was leaving. Martha offered a "Good luck, dear," a hug, and an encouraging smile.

Kate tried to control her breathing in the elevator, but the closer she got to his floor the more her heart raced. Martha had been right: they were terrible at communicating, having relied on looks and innuendos for years, and they were way overdue for an actual conversation. Before she knew it she was standing at his door, knocking before she could talk herself out of it.

The door opened almost immediately, Castle's neutral expressing morphing into something darker as he took in her presence. "What is it, Beckett?" he asked coldly, his body filling the door frame so she couldn't barge her way in.

"I need to talk to you."

"Okay." He didn't move.

Kate flicked her eyes past him. "Can I come in?"

"No. You want to talk, so talk."

"Fine." Kate steeled herself and stood straight, bringing herself as close to his height as her flats would let her. "I'm sorry, Rick. For everything. I'm sorry that I lied. I'm sorry you found out how you did. I'm sorry that it's taken me this long to say something."

"Why'd you lie?"

She huffed and pushed Castle out of the way, stepping into his kitchen. She knew he was trying to protect himself, was using the apartment as a metaphor for his heart, but she'd be damned if she was going to stand in the hall for this conversation.

"I was scared." The words felt weird; she'd made that confession to Dr. Burke months before, but hadn't vocalized it since. "When you told me, I was afraid it was in the heat of the moment, that maybe you didn't actually mean it. But then when I came back, I knew that you did, and – Rick, I am so, so sorry."

Castle finally took a step forward into the kitchen as well, placing himself on the opposite side of the island. "It's been almost a year, Kate. It's taken you this long to what, figure out how to put me down?"

"No. You know why I was so afraid, why I lied to you in the hospital?" Kate took a few steps around the island so she was in front of him, placed a tentative hand on his cheek, allowed a smile when he didn't pull away. "Because I loved you too, I still do, and if you hadn't meant it I would be absolutely heartbroken. I did it to protect myself, and it was selfish, and stupid, and I will apologize every day for the rest of my life if you want—"

He cut her off with his lips crashing against hers, his hands moving of their own volition to tangle in her hair. The kiss was slow and deep, saying everything that had gone unsaid in the past months. "Kate," he gasped when they finally parted, both trying to catch their breath.

"I'm sorry—"

"Stop apologizing." Castle stared into her eyes, searching for anything that told him this was a dream or too good to be true. It wasn't – all he saw there was love, and it broke his heart, because he had to break hers. "There's something I have to tell you."

Beckett took a step back at his serious tone. "You don't love me anymore."

"No. I mean, yes. I still love you. I always have." He took a deep breath, took her hands in his. "I've always loved you, Kate, and that's why I did something, and that's why I have to tell you."

"Castle, spill. What are you trying to say?"

"It's about your mom."