"Wish I had a nickel for every time I heard that," said Castle, but his tone was grim. "Who is it that's going to kill me?"

"The people behind the LokSat operation," said Kate, her voice muffled against his shoulder. "The people who had Rachel and the others killed."

"Wait." He held her at arm's length, looking appalled. "That's what you're doing? You're going after LokSat?"

"I have to."

"Have to?" he asked. "Because your team was killed and you feel responsible? Because Bracken's dead and you need a new mission? This isn't Agents of S.H.I.E.L.D., Kate, and LokSat is not Hydra. You are not the only one who can bring down the Big Bad, and going at it alone is going to get you killed. Whether your obsession is with justice, or personal responsibility, or protecting what you love, you need me. How many times do I have to tell you that?"

The word obsession interrupted her attempt to gather her thoughts.

"What do you know about obsession?" she asked, equal parts bitter and curious.

"Well...there's a Kellerman novel with that title...a fragrance by Calvin Klein, a Brian de Palma film that's heavily influenced by Vertigo…" It was his usual spiel, rolling out apparently unrelated, usually trivial facts on cue. This time it didn't seem to roll as easily as usual. He probably thought she was trying to distract him.

"Right," she interrupted, as usual. "Do you know how it feels?"

She expected him to make a reference to his pursuit of her, but instead he said, "Only in the temporary sense, on every case we've had, in every story I write. I feel like I can't rest until I know the whole story. You know that."

"Yeah, I do," she said. "And then there's that cop you chased for four years."

Castle looked startled.

"No, no," he said. "That wasn't obsession, Kate. That's love. If it'd been an obsession I would have lost interest the minute you showed any interest in me. I'd know how the story would end, and I'd find something - someone - else to go after. I've done it before, much to my shame, but not for a long time."

Kate wanted him to understand this, as far as she could explain it. She sat down on a stool and took a deep breath.

"I've always had that side to me," she told him. "When my mother was murdered, once the grief became manageable, my only purpose was to discover the truth about her death. You've heard me talk about it - how it consumed me. I forced myself to back away, and in the process whipped myself into shape as a supercop. Youngest woman to make detective. Head of a squad of top-notch guys like Espo and Ryan. Hand-picked for Homicide by Roy Montgomery."

"It wasn't enough, though, was it?" Rick asked. "That's when I entered the picture. You were so driven to get to the bottom of a case - I recognized a kindred spirit, someone who wouldn't leave the story alone until the bitter end. I was amazed - I still am."

"Thanks, but - " Kate shook her head. "I don't know if that's a good way to go about living - I'd burn away to ashes and rise again with every case we landed. You said it yourself - I don't back down. And that works, for homicide cases - but not so much with relationships. It either scared people or fascinated them, like I was a case study or a lab rat. Or they'd say I just needed to find the right man. Or woman."

They'd had this conversation, more or less, long before, over their previous relationships and why they didn't work out, always promising each other it would never happen to them. Who was she kidding?

"I did find the right man," she said after a minute. Looking in his eyes, she said it again. "I found the right man, Rick. I just don't know if I'm - the right woman for you."

Now he looked downright shocked.

"Hey," he said, taking her hand. "You are, Kate. You are the only woman for me, not just because of our history, or because you'd make a stunning trophy wife, or because I think I'm doing you a favor - please! - or even because I think you're perfect and beyond reproach. Because I don't."

She snorted a laugh. "Definitely not that."

"I'm going to reproach you some more, then. Neither of us is a model of mental health, Kate, but then, neither is anyone else in this world. The question is, what do you do with your own personal twist? Do you succumb to it, fight it, deny it? Or do you use it?"

Once more, a voice from the past. Javier Esposito, holding out the rifle used to shoot her in the cemetery.

"You think it's a weakness? Make it a strength."

"I have used it," she replied. "I was just saying."

"Like me - you use your obsession, your drive, every day, to find the truth. And once you do, you get back up and start over with another puzzle. What about the really tough puzzles, though? Like your mother's murder? Mysteries that take years to solve, or even to identify?"

"But we did," she said passionately. "We solved it. Bracken was put away, he was going down for life."

"Yeah, he was," said Castle, watching her. "And then someone killed him. Stole your closure, I'm guessing."

That thought had occurred to Kate, and she'd denied it, shoving it away behind the more noble cause of bringing justice for her dead comrades. Now Rick Castle mentioned it as though reading her mind, and how could anyone, even Castle, know her that well?

She reached for the drink Castle had poured and downed it in one swallow.

"He got what he deserved," she said.

"But not on your terms."

She rounded on him. "Does it matter? The man who ordered her death is dead. The man who carried out the order is dead. Why should it matter how?"

"It matters to you," said Castle. His voice was gentle. "Because now that they're dead, you feel like you should be able to move on...but you can't."

Kate just stared. He'd come up with plenty of insight into her inner self over the years, but this was uncanny.

"Where are you getting this from?" she choked out. "What makes you think - ?"

"From you," he told her. "From what I know about you. You can't bring yourself to move on, settle down, be happy, because your whole life has been about bringing closure to other people. And now you feel you have to pursue whoever is behind LokSat, and the AG team's deaths, to the gates of hell, because until he's dead, your story is not over."

"And once he's in the grave?" she said. "I thought, when I imagined it, that that would give me peace, but now I'm not so sure. I can't be sure. And I can't put you through that, Rick - you didn't sign up for my brand of torture."

His hand was warm on her cheek, sliding to the back of her neck, sinking his fingers into her heir.

"I did, though," he murmured. "I may not have known, when I first started following you, to what heights and depths you would go for your cause. But Kate - You think we made it through all those worst case scenarios, misunderstandings, trials and tribulations, only to fall apart now? When we need each other the most?"

"And then?" Kate persisted. "If we make it through this case? What if something else rears its ugly head, something more I can't let go?"

"Remember Roy Montgomery," said Castle. "There are no victories, only battles. You find a place to make your stand. And you will always have someone to stand with you. Me."