COUP DE GRÂCE
PART ONE

"How dangerous is he?"

Castle considers the man sitting across from him, the father of the woman he loves, unsure of how much to tell him. Jim Beckett lost the love of his life twelve years ago, and he's in danger of losing his daughter now. Castle can't imagine the worry, doesn't know how much he'd want to be told, if it was Alexis in this situation.

But one of the few things he knows about Jim is that he'd want the truth. Kate had told him that much once, that the Becketts are no-nonsense sort of people, her dad especially. So, Castle doesn't hold back, just tightens his grip on his mug.

"He's a trained killer."

Jim nods, his gaze dropping to his own mug, and he doesn't seem at all surprised. "What happens when she finds him?" He looks back up at Castle. "I've already lost my wife over this. I've already lost…" He trails off, takes a deep breath. "No, look. It took me years but I've made my peace with that. But Katie? She won't listen to me. And she won't back down. Not unless someone can convince her that her life is worth more than her mother's death."

Castle can only stare as the older man drains his mug and stands.

"Look, she cares about you, Rick. And unless you're a lot dumber than you look, I know you care about her. Don't let her throw her life away." He holds his hand out, and Castle stands as he takes it.

"I'll do what I can," he promises, and he will, he'll do whatever the hell he can to keep Beckett safe. "I wish we'd met under better circumstances."

Jim huffs out a laugh. "You and me both. Thanks for the coffee, Rick."

Castle leans against the closed door after he shuts it, and closes his eyes. Kate is spiraling; he sees it, her dad either sees it or has anticipated it. Hell, a blind person could see it. She's falling down the rabbit hole of her mother's murder again, has taken a hold of their single lead and dug her claws in, and if she isn't careful, it will consume her, likely kill her. He won't let that happen.

He can't let that happen.

He scrapes his hand over his face, muffling a curse, and steps away from the door. He needs to see Kate. Tonight. Maybe he can get to her before she does something stupid.

His phone rings when he's slipping on his shoes. He almost ignores it, but when he remembers how late it is, he glances at the screen to see Montgomery's name glaring at him. His brows furrow in concern and he swipes to answer.

"Hello?"

"Castle, it's Roy. I need your help."

Rick gets to the hangar moments before all hell breaks loose.

Montgomery hadn't told him much, just that he needed to get to the hangar so he could get Kate out of danger. Save Kate, Roy had said. It doesn't matter what I did, I just need you to get Kate to a safe place.

So he carries a kicking and screaming Kate out of the hangar, traps her against her own car, his hand on her cheek, his heart breaking as she fights and sobs and eventually just sags against him.

When they hear the gunshots, he doesn't have the energy to hold her back when she pushes him away and runs back to the hangar. And when she kneels over Montgomery's lifeless body, he can only stand there and watch.

He follows her back to her apartment, where Ryan and Esposito are waiting. She'd asked him to call them, couldn't bring herself to do it herself. He doesn't tell them what happened, just that they need to meet him there.

Ryan pulls him aside as soon as they're in Kate's apartment, his grip on Castle's arm firm. "What's going on?" he asks in a low voice.

Castle just shakes his head.

Kate does most of the talking, explains what happened in the hangar in a low, controlled voice. She's the picture of calm, but Rick can hear a slight tremor, recognizes the tone. She's barely holding herself together. "No one outside this immediate family ever needs to know about this," she says when the boys are filled in. "As far as the world is concerned, Roy Montgomery died a hero."

The boys leave shortly after their agreement, but Castle loiters by the door, watching as she disposes of the empty beer bottles. She pauses at the sink, hands gripping the counter and head bowed, and Castle can see her shoulders start to tremble.

He takes a few cautious steps towards her, not wanting to startle her in case she thinks he left. But his foot lands on a creaky floorboard and he freezes, but when Kate just slightly turns her head towards him, he joins her in the kitchen. He doesn't know what to say, what can alleviate the pain she must be feeling, so he just leans against the counter and says her name.

"You should go," she says quietly, head bowed. "Be with your family."

Castle shakes his head. "I'm not going anywhere. Not until I know you're okay. That you're safe."

She exhales and pushes herself from the counter. "I'm fine." She walks into the living room, and he follows, at her heels as usual.

"No, you're not," he argues. When she turns and crosses her arms with a glare, he doesn't flinch, just squares his shoulders and sets his jaw. "Montgomery's dead, Kate. Everybody who's been associated with this case is dead."

"Including Lockwood."

"He was just a hitman, you know that. They'll just send someone else."

Kate throws her arms out. "What the hell am I supposed to do? Walk away?"

"Yes." He hates himself a little for even saying it, but he can't lose Kate. He won't. "What's Roy's sacrifice if you get yourself killed? You can't avenge your mom's murder if you're dead too."

"I can't believe you just suggested that," Kate says in a low voice, shaking her head and turning from him. "I won't stop, Rick. I can't."

Rick hesitates just a moment before following her further into her apartment. "So what, you'll sacrifice yourself for the greater good?" She's mad, he can tell by the rigid set of her spine, but she has to see reason.

He can't lose her to this.

"At least think about what it would do to the people who you love you." When Kate just scoffs and turns back to face him, he keeps approaching her, stops just feet front of her. "What would it do to your dad? Or Josh?"

"And what about you, Rick?" She takes a step closer to him, eyes blazing, jaw set.

"Of course I don't want anything to happen to you. I'm your partner. Your friend."

"Is that what we are?"

She's just inches from him, close enough that he can see her eyes darken, brown taking over the green, can see the flare of her nostrils.

He shakes his head. "No, you know what? I don't know what we are. We kiss, we never talk about it. We almost die, frozen in each other's arms, and we never talk about it. Something could have happened in LA, but you fucking walked away." He hears her sharp inhale at the mention of the other city, but he barrels on. She needs to know how he feels, that there are others who care if she continues this suicidal quest for justice.

"So I don't know what we are, Kate," he continues, "but I know I don't want to watch you throw your life away. I care about you too much for that."

"Care about me, huh? Is that all?"

"Kate-"

"Tell me something, Rick," she snaps, his name cold on her tongue. "Is it me you care about, or your precious Nikki Heat?"

Castle's jaw drops. He sees regret flash in her eyes as soon as the words escape, but she stays firm, her whole body rigid. "You think that's what I care about?" he asks after a few long moments, after he's composed himself. "You think after all this time, it's still about the books?"

Kate crosses her arms over her chest. "Then what the hell are you still doing here? Why are you following me around?"

"You know why."

"I want you to tell me."

Castle has always been able to talk his way through anything. Words are his specialty, his way of life, but at that moment, they fail him. So he does the first thing his instincts move him to do.

He brackets her face in his hands, and kisses her.

It's rough, and hard, but he persists, feels her start to give beneath the hard press of his lips after just a few moments.

She grips the front of his shirt as she opens beneath him, tongue meeting his, a moan escaping her throat. As soon as her hands slide along his sides, his fall to her hips, and he tugs her into him, groans when their bodies press flush against each other.

"You bastard," she gasps when they part for air, but then her hands are in his hair and she's pulling his head down to hers again.

Castle lets her take control, lets her guide him back towards the living room and onto the couch, where she climbs onto his lap, working at the buttons on his shirt. His hands slip beneath her shirt, but before he can lift it she grunts and abandons his half-unbuttoned shirt for his belt. "Kate," he breathes, leaning back just far enough so he can see her eyes, dark, consumed with what he can only assume is lust.

She shakes her head and leaves his lap long enough to undo her jeans and shove them down her thighs. "Shut up."

She doesn't see him until the funeral.

He calls her, of course, but she ignores him. The sex had been...intense. Angry sex on her couch was not what she'd anticipated for their first time - at the very least, she'd imagined a bed - but she can't stop thinking about it. About him.

About his mouth on her, his hands, his…

She shakes her head as she steps out of the shower, wraps one towel in her hair and another around her body. Her phone rattles on her nightstand, Castle's smiling face looking at her from the screen. She declines the call.

He's called her 27 times in the four days since their fight, and she's declined or ignored every single one.

Sighing, she takes her uniform from the closet as she waits for the telltale beep of a left voice mail. A beep that doesn't come.

She sees him arrive just minutes before the funeral starts, with his mother and daughter in tow, but there's only enough time for a look before they have to carry the casket to the grave.

His look is full of longing, longing that she has to ignore.

"Kate-" he says quietly as they gather, but she shakes her head.

"Not now."

She thinks she manages to hide her surprise when he joins her at the podium after the flag is presented to Evelyn, but he's speaking after her, shows her the index cards in his pocket. So she simply gives him a small nod and steps up to the microphone.

Losing her mother had been devastating. Losing Roy, after finding out that he'd inadvertently started the events that had led to her mother being killed, is unbelievable. It feels like a nightmare. Even as she begins to speak, even as she can see Rick gazing at her from her peripheral.

He turns his head just once, but in that instance, everything changes.

She doesn't know what the sudden pain is in her chest, doesn't register Castle's shout until she's on the ground, and he's hovering over her.

He's saying something, something she doesn't understand, but as she tries to focus on his fading face, she hears eight words. Eight words that she knows will change her life.

"Kate, I love you. I love you, Kate."

But as the world fades to black, she wonders if she has any life left for him to change.