"This will be my last case," he said, looking at her with a look in his eyes that she couldn't quite place. She remained silent for a few moments, looking in his eyes and trying to identify the emotions – the reason behind his sudden decision to leave.

"What?"

It was the only syllable her confused brain could force out of her mouth.

"I just feel like it may be time for me to move on. There really isn't anything left for me here anymore." At his words, she felt her heart constrict, her head spin. Nothing left? She thought that they had been making progress in the last few weeks.

"What is that supposed to mean?"

"I have a lot of writing to do. It's time for me to stop wasting my time playing cop." She felt her heart drop, stung by his words, but anger and annoyance quickly masked her hurt.

"Wasting your time? Is that what you think you've been doing?"

"You tell me. I come in here every day when I should be at home writing to follow you around and pretend to be a cop."

"What about coming in here for inspiration? How is that a waste of your time?"

"I have enough to finish the latest Nikki Heat and that's all I'm contracted for, so I figure I can just concentrate on finishing it and be done." Something in his tone told her that he wouldn't be done with just the books.

"Done? Just like that?"

"It's not like there's another reason for me to stay." He looked at her after that and she was finally able to identify the emotion in his eyes – anger. A fiery anger she had rarely ever seen from him.

"You're my partner. That's a reason to stay."

"Let's be honest, Kate. I'm not your partner, I'm a writer who happens to follow you. It's time for me to grow up."

"Oh, that's rich. This is not about growing up, Castle. You can't just up and leave like this. What about Ryan? Esposito?"

"I'll keep in contact with them, they're still my friends." She didn't know where this was coming from, but she sure as hell didn't like where it was headed.

"And what about me? Will you stay in contact with me?"

He didn't respond immediately, giving her the only answer she needed.

"Are you kidding me? After everything we've been through you're not even going to tell me why you're leaving like this?" As her voice rose, they began to draw the attention of others milling about in the bullpen.

"What else is there to say, Kate? I've missed countless deadlines because of this little hobby over the years. Nikki Heat is almost complete and I'm done waiting for inspiration for a happy ending to the story."

The way he looked her straight in the eye made her fully aware of the fact that he wasn't just talking about the books. Flustered, she looked away, not knowing what to say to him. At her lack of a response, he shook his head, letting out a frustrated chuckle. He was still for a few moments and she would swear she could see the gears turning in his head as he thought about his next move.

"I should go. People are staring."

He stood to go and on reflex, her hand shot out, grabbing his wrist as he went to walk past her.

"Don't go," she said, barely a whisper.

"Damnit, Beckett. Let go," he growled.

"No. Not until you look me in the eye and tell me a good reason for you to be leaving like this."

His back still turned to her, she could see his shoulders tense as the anger boiled in him.

"Just tell me what I did, Castle."

He took a deep breath and she braced for what he was seemingly about to say.

"You heard me," he said, without turning around.

"Saying you need to work on your books is not a good enough reason, Castle. That's never driven you away before."

"I didn't mean today," he said as he turned around. Looking her in the eyes, he simply stated it again, though this time she could see the anger, now laced with a deep hurt in his eyes.

"You heard me. You remember."

If she didn't know any better, she would say that her heart stopped in that moment.

"Castle…"

"I'm done with the games, Kate," he whispered harshly. "Done." With that he turned to walk away, her hand slipping from his wrist, her mind still in shock. He was almost to the elevator by the time her senses came back to her. She quickly stood, running to the elevator.

"Castle, wait," she pleaded.

"No. I am done waiting."

"Castle, please just listen to me," she said quietly, now aware of how many spectators their argument was gaining. He stopped and looked over at her, the anger she saw in his eyes almost causing her to take a step back from him. His next words came out in a quiet growl.

"No. You listen to me. I'm done with all of this bullshit, Kate. Either say what you really feel, or I swear I will walk out of this door right now and not look back."