AN: Sorry for the delay on this one. Homework is kicking my ass.

Castle knocked on his partner's door, more nervous than he had been in a long time. Getting her off the case was the right thing to do, he just wasn't sure he could get her to do it. He owed it to Roy and her dad to try. He couldn't lose her to this case. It would destroy him to lose her. He knew she needed his emotional support, but as her partner he couldn't support her continuing on a path that led to death.

Rick needed to be there for her, but Castle needed to pull her away.

He was so lost in his own internal battle that he didn't react to Beckett opening her door right away. She waited for him to say something before she realized he was lost in thought, then spoke.

"Rick?" Her voice was softer than he expected. He assumed she would be angry at him for coming over after she specifically told him not to, but maybe she'd softened towards him more than he knew.

"Kate," he breathed back, pausing a moment before continuing. "Can I come in?"

"Of course," she said with a nod, moving to the side to let him through.

Castle mentally ran through everything he needed to tell her. "Sorry for surprising you like this. I know you wanted to be alone tonight."

"It's okay, Rick. I probably shouldn't have shut you out anyway. I know you're only trying to help." They shared a moment of silence as Rick took in the words she had said. She trusted him. "Did you find something?"

"Yes, actually," Castle said. "We went over Raglan and McCallister's old arrest records, and you were right. There was a third cop that was with them on a lot of those arrests. But then, someone went back into those reports and removed their name. So, Ryan and Esposito are right now looking into who was running the records room back then."

"And?"

Beckett's response was not what he had anticipated. He had hoped she would have some theory to build off of what they had found. "And what? That proves that there's a cover up."

She sighed. It wasn't enough information to warrant coming all the way over without at least texting her first. Castle had something else he wanted to talk to her about and this had been his excuse to come over. He wanted to talk about something he knew she wouldn't like.

"Castle, what's goin' on? You wouldn't come over unannounced unless you had something else to tell me."

He was caught red-handed. He knew what he needed to say, he just worried that their relationship wouldn't survive it. "Beckett… Kate, everyone associated with this case is dead. Everyone. First your mom, then Raglan, then McCallister. You know they're coming for you next."

"Captain Montgomery's got a protective detail on me."

"That you and I both know won't be enough to stop Lockwood." Beckett shifted slightly at the statement. As much as she knew it was true, she was unwilling to admit that Lockwood would find her before she found him. "Think about what they're up against. Professional killers? You know me, Kate. I'm the guy who says we can move that rubber tree plant. But you know what? I don't think we're gonna win this."

"Castle, they killed my mother," she said, anger rising in her throat. "What do you want me to do here?"

"Walk away." It pained him to see the flash of anger in her eyes. He knew she felt betrayed. He was supposed to be with her until the end. "They're gonna kill you, Kate." He felt his voice crack at the thought of her gone. His own nightmares had been plagued with her dying ever since he was shot, and he couldn't let his worst fears be realized. He had to get her to stop before he lost her. "A-And if you don't care about that, at least think about how that's going to affect the people that love you."

The silence that filled the room was heavy and full of grief for the events to come. Castle had given her a choice. Dig her heels in and risk death, or let go and risk not knowing. He was right, they would kill her. She would spend the rest of her investigation under constant threat of being taken out.

But it wasn't enough to stop her.

"I think you should go, Castle," she said quietly after a minute had passed.

"Kate, please, I —"

"You don't want to get hurt? Fine. Then walk away. I don't need you on this one." It hurt her heart to even say the words. She didn't want to lose Castle, but she refused to step away.

"Don't make me do that, Kate. Don't make me leave," he all but whispered, tears threatening to spill in his eyes.

"Either you're with me or you're not. I'm not backing down." It took all her strength to give him an ultimatum like that. She didn't want him to leave, but she didn't want him to blame himself if she died.

"We can't win this, Kate."

She took a deep breath and held it, steeling herself for what she had to say next. "Then get out."

And without another word, Castle had to admit defeat. He couldn't support her walking to her death. He couldn't bear to watch. He walked out of her apartment hoping that she would get lucky somehow. It might have meant the end of her relationship, but he hoped it didn't mean the end of her life.