Disclaimer: All things "Castle" belong to ABC & Co.

Author's Note: Kate might say afterwards that she never doubted but I never believed it could be quite as simple as that for Kate to hear/read about Castle's alleged involvement with Tessa in "Probable Cause," so this is exploring how Kate learns to believe in Castle.

Finding Faith

She didn't believe it.

She absolutely didn't believe it, Kate repeated to herself.

She didn't.

It wasn't—it couldn't—be true.

Castle wouldn't—couldn't—could never use physical violence against a woman, let alone kill anyone in such a gruesome fashion.

The murder, she didn't believe. She could never believe that. Not Castle. He couldn't do that. She was a homicide detective; she knew that almost everyone could kill when it came to it and she knew that Castle was capable of violence in defense of those he loved. But murder in as cold-blooded a way as Tessa had been murdered—no, Castle couldn't do that.

The murder was one thing; the… affair with Tessa—could that be true?

No, it could not. Castle wouldn't—he would never cheat on her.

She knew that. She believed that. She did.

It wasn't true. It didn't matter what his reputation said. It didn't matter what the evidence said.

She didn't believe it, she told herself yet again. And yet…

Did she really know? Was it ever possible to truly know another person, what they were capable of? She saw the worst of what people could do every day; how many times had she heard someone swear up and down that someone they were close to wasn't a killer only to have it be proven wrong?

She still didn't believe it. Not about the murder or about the affair. She didn't.

But there was evidence. She needed to know, had to find out the truth. It was what she did, wasn't it?

She hadn't looked at it yet, the printout of the emails sent to Tessa that Ryan had handed to her, his blue eyes filled with a mute apology and reluctance that she'd never seen in him before. An apology that had slashed at her because it had occurred to her that Ryan—Ryan, of all people, who still liked to believe the best about people, rather like Castle—she mentally flinched—believed it.

She reached out a hand that she was only vaguely surprised to realize was trembling to pick up the sheets of paper.

She didn't believe it, any of it, but that didn't make it easier to read, knowing what they purported to be.

She looked down. The emails were labeled by date and time. They started in August. Just before their three month anniver—she ruthlessly squashed down the now-painful memory of that day, the way Castle had… When she'd still been so blissfully happy, never even suspecting—no, she cut off the thought. There was nothing to suspect because she didn't believe it. It wasn't true.

And yet… She couldn't help but go on reading, random messages seeming to leap out and sear her eyeballs.

I really like you, Tessa. Have dinner with me? Rick.

Tessa, can't wait to see you again. Rick.

Best. x First. x Kiss. x Ever. xxx Rick.

A sob escaped her before she'd realized it and she clamped a hand to her mouth, choking any more back. She didn't believe it, she told herself again, but… But it sounded like him. The boyish exuberance, the use of superlatives. She could hear his voice in her mind saying those words.

She choked on another sob and unbidden, a tear rolled off the tip of her nose and dripped onto the page, staining it. Unwilling but unable to help it, like the proverbial train wreck, she looked back down.

I think I love you.

She gasped for breath, feeling as if she'd just been punched in the sternum—or stabbed in the heart—and abruptly flung the sheets away to land in a haphazard mess on the floor.

No! No no no! She didn't believe it. She couldn't believe it.

She had to know the rest.

She reached out with trembling hands, her movements carefully controlled as if she feared that she might shatter into a million pieces if she moved carelessly, and picked up the sheets again, forcing herself to go on.

Oddly, she thought, in some ways, the worst part might not have been the more overtly romantic ones but the other ones, the ones that apologized, that claimed he just needed more time to simplify his situation. It was all so familiar—she'd seen it all before, so many times—the words of an unfaithful man to the other woman, making promises for some future time, always some future time, when he would tell his wife/girlfriend the truth and then they could really be together, so many empty promises, stringing a woman along. The words of a man who wasn't doing right by his lover—and never intended to either.

She'd seen it all before-but she'd never before been on the other side of it. Had never experienced it from within.

It was the familiarity of the pattern, the story, that gave the whole thing a horrible, devastating plausibility. Because this sort of thing happened every day. She saw it every day.

How could she be so confident that Castle—only Castle—would be the one man who would never do such a thing? That their story was the exception to the rule.

He wouldn't do this. He wasn't like that. He wasn't that man. She knew that.

She started violently at the sound of a knock on her door, for one crazy second convinced that it had to be him—that she'd just fallen asleep and dreamed this whole nightmare—but then she heard Lanie's voice through the door.

"Kate? Honey, it's me. Javi called me."

She hadn't dreamed this.

Kate put the papers back on the coffee table with shaking hands and rose on knees that felt unsteady to open her door for her best friend, not quite able to decide if she was glad or not that Lanie was here. Company might help, especially that of her closest female friend, but it might also hurt, a reminder of the person who wasn't here, the person she always automatically sought for comfort now.

Because even now, the person she really wanted, needed, was Castle. God, she thought wildly, how was it that in spite of everything, the insidious doubts creeping into her mind like poison, she still wanted him.

The person sitting in a cell right now. She flinched.

Lanie took one look at what must be her ravaged expression and gave Kate a hug. "Oh, Kate…"

She drew back and met Kate's eyes. "I have alcohol or if you want, I can just listen or be a shoulder to cry on. Whatever you want, Kate."

Kate tried for a twitch of her lips as the closest substitute for a wan smile but knew she failed. She only retreated back to her spot on her couch as Lanie closed the door and followed.

"Javi told me," Lanie finally said, breaking the silence, her voice and expression compassionate.

At any other time, Kate might have made a quip about Espo's propensity for gossip but she couldn't manage it. In some corner of her mind, it occurred to her that this had spared her the scolding she had been expecting to receive from Lanie when Lanie found out about her and Castle, about the fact that Kate had kept it a secret for so long. Now, that surprise was over, no longer mattered in the wake of this horror. She only nodded dully, grabbing a tissue and swiping at her wet cheeks.

Lanie glanced down at the papers on the coffee table. "Are those the emails?" she ventured.

Kate nodded again.

Lanie reached out and picked them up. "Can I…"

Kate waved a hand in a wan gesture of permission but Lanie didn't, after all, read the emails, only watched Kate, and after a while, Kate began, not quite steadily, the words coming as a story. Not that she believed it. She didn't. Really. "They started up about eight weeks ago, according to those emails. He met her after one of his book signings and he asked her out for coffee and that was a… It was just a couple weeks after we started seeing each other…" She swallowed back a bubble of hysterical laughter that had more in common with tears, afraid that if she let out any sound, she would fall apart completely. 'Seeing each other'—god, what a bland euphemism to use! As if that even came close to describing what she'd found with Castle—not just the physical passion but everything else, the utter peace and comfort of being in his arms, the way she'd felt at times as if she were melting into him so that she might never be whole again without him…

God, would she ever feel that again? She sniffed and swiped at the tears that escaped.

"Oh sweetie…"

"He told her that he needed to keep it a secret because he was with someone else…"—oh god, Castle…—and then when he tried to break it off about a week ago, she threatened to go and tell his girlfriend. He offered to come over to her apartment to talk things through and that was the night of the murder."

"He had motive," Lanie observed quietly, repeating the obvious truth that had been banging at the walls of her incredulity since Ryan had told her. "What did Castle say when you talked to him?"

She swallowed back another sob. "He said that the emails were faked. He said that he never wrote that story and he was being framed." She inwardly flinched at the memory. She'd never seen Castle look so… desperate. And for once, she'd thought she would have given anything to have him come up with a crazy story about alternate universes or evil twins or shapeshifters. But he was too shaken, too terrified for that, knew it was too serious for that.

"You should have seen him, Lanie. He looked like a little boy, he was so scared." She choked on another sob. "I know him, Lanie. He is an immature, egotistical, self-centered jackass sometimes…" True but she found all that endearing and he was so much more than that too, had proven it over and over again. His kindness, his empathy, his courage, his loyalty… "But he's not this."

"Are you sure?" Lanie ventured gently, a world of sympathy in her eyes and voice.

Was she sure? The evidence was damning, she knew that. God, she felt that. Her heart felt as if it were being squeezed in a vise and it physically hurt to breathe, felt as if she'd broken a couple ribs. Even the suggestion of it was almost crushing her chest but did she believe it? Did she believe Castle had done any of this, betrayed her like this?

And was she sure?

"I think so," Kate managed to say but her voice cracked and then she was crying, again, and Lanie quickly stood up, tugged her into a hug and for a moment, Kate just let herself go, let herself be held by her best friend as she cried out her fears, her reluctant, insidious doubts, her hurt.

It helped, a little, but it didn't even come close to the comfort, the safety, she'd always found in Castle's arms.

"I… I love him, Lanie," she gasped. She did. She might not have admitted it in so many words to anyone else before but she did. Had loved him for… oh, she could barely remember how long now. A year, longer? "I do… I really love him…"

"Oh, honey," Lanie crooned, patting Kate's back. "I know. And he—" Lanie broke off abruptly but Kate somehow knew what Lanie had been about to say. He loves you too.

But Lanie had stopped herself. Lanie… doubted. Didn't want to say it.

He loves you too.

He did.

He did love her.

The thought of Lanie's doubt had her, perversely, becoming more certain.

Castle loved her.

She knew he did.

He'd said so.

But it wasn't only that. Kate was, sadly enough, too much of a cynic to believe so entirely in just a person's spoken words. Not when she dealt with people's lies every day.

No, it wasn't only that he'd said the words. It was… the other things. It was… the way he held her, the way he touched her, the way he brought her coffee just the way she liked it. It was the things he'd done, said, in his sleep. When he'd been unconscious. Certainly unable to plot or consciously keep secrets. Sleep revealed.

Kate had been sleeping beside Castle for months now. She knew his sleeping patterns, his habits. She knew the sound of his occasional snuffling noises when he was particularly tired. She knew how deeply he tended to sleep—but also knew that if necessity called for it, he could snap to immediate awareness. He had more than once woken her out of a nightmare because he had somehow sensed the disturbance to her sleep.

And she knew he loved her. Because of the way he reached out for her. Because of the way he mumbled her name in his sleep. Because of the love, mingled in with some awe even now, in his eyes when he woke up to see her, as if waking up to her was a privilege, a gift. Because she knew he dreamed about her—not just happy dreams or even erotic dreams, although she knew he had those too, but nightmares about her getting hurt. He still had nightmares about her shooting, had woken her with his tears as he cried even in his sleep.

He had shown her that he loved her over and over again, not just since they'd gotten together but for years now.

She pushed herself upright, drying her tears with a still somewhat shaky hand. "Thanks, Lanie. I'm… better now, I promise." She met Lanie's eyes, feeling some of her usual Beckett-ness returning to her. As if, in some strange way, she needed her faith in Castle to be… Beckett again.

She hadn't realized it until now, how important her trust in Castle was. In a life in which she'd been let down, betrayed, again and again by people she cared about, her faith in Castle had become… like gravity, allowing her to stand upright. Her trust in him was the bedrock of her existence—and if she ever lost it, if her trust in him was ever shattered, she suddenly knew she'd never recover from it.

Castle hadn't done this. He couldn't have done this.

Kate could imagine very limited circumstances in which it might be hypothetically possible that Castle would cheat—if he was drunk and they'd had a serious fight, maybe, maybe—but this, a clandestine affair for weeks, living a lie, no, he simply was not capable of that.

He wouldn't do that to any woman but it was even more incredible to think he would do that to her. After he had waited for her, forgiven her so much, shown her time and time again how much she meant to him…

He hadn't slept with Jacinda all those months ago. Even though they hadn't been together at the time, even though he'd been heartbroken and angry at her.

"Castle didn't do this," she repeated. "I know he didn't."

Lanie's expression softened. "If you believe it, then so do I."

"He…" loves me. The words failed her, she couldn't say that aloud, not now, not to Lanie. "He wouldn't do this to me," she said instead.

"I believe you, Kate."

Kate nodded. "Okay. Thanks for coming, Lanie, but I think… I'll be all right now. I just… I'm really tired," she explained, not untruthfully.

Lanie hesitated, studying Kate for a long minute—loyal friend that she was—but then she nodded and stood up. "Okay, Kate, if you're sure, but call me if you need anything, okay? I'll come running."

"I know. Thanks, Lanie." This time, it was Kate who initiated the hug before she opened her door again.

"Call me anytime, Kate. I mean it, girl," Lanie instructed.

"Yes, Lanie, I will," Kate answered dutifully. "Good night." She paused. "If you talk to Espo, tell him I'll need him to be sharp tomorrow."

"Will do. Try to get some sleep, Kate."

Kate nodded and closed the door after Lanie before returning to the couch again. She hadn't lied, she was tired, but she already knew she wasn't going to manage to get much, if any, sleep tonight. Not without Castle.

She dropped back down on the couch and stared at the sheets of paper with the emails.

She had to do this. Because if he hadn't had an affair with Tessa—Castle was right and he was being framed. Someone had gone to a lot of trouble to come up with all this evidence. And someone else had obviously murdered Tessa.

From some corner of her mind, she heard his voice, Other people come up against a wall, they give up. Not you. You don't give up. You don't back down. That's what makes you extraordinary.

He'd had such faith in her, even so many years ago. Before… they'd ever fallen in love, before they'd even really become friends.

She could do this, she had to do this. For Castle.

She pictured his so familiar, so beloved face, the way he smiled at her, the way he looked at her with his whole heart in his eyes.

She let his image infuse her with courage and she reached over and grabbed the sheets of paper again.

She needed to read through the emails again. To prove his innocence. Find the story that would make the evidence make sense.

She sucked in her breath and let it out again, mentally steeling herself, shoving aside any and all emotions and calling up every ounce of her training. Looking at this like she would any other case.

She was a Grade One NYPD Detective. And she could not let Castle down.

She started to read through the emails, considering everything, the dates, the times, for any anomaly, anything she could use as proof for Ryan and Esposito. Ryan, she didn't doubt, would be willing, even eager, to believe her, but Espo would require more.

She didn't realize she was biting her lip until a sharp sting and the tang of blood in her mouth made her start and realize she'd actually drawn blood and forcibly stopped herself, releasing her poor abused lip and clenching her jaw instead.

The messages started around the middle of August and she forced herself to read them in order, all of them this time. Follow the story as told.

Some of the emails did sound painfully like Castle but they were mostly… brief, not as wordy as she would expect from him. And he never mentioned Alexis or his mother. It was… odd, certainly for Castle, it was odd, but not definitive. Whatever else, she knew Castle as a father would have protected his daughter from a fling he was having. She knew that much about Castle just from her familiarity with his publicity over the years, how fiercely he protected his daughter. And yet… it still made the emails sound less Castle-like. They were so carefully controlled. He didn't babble, didn't digress.

It could be said they were damning in that way, a man as clever as Castle, who was deliberately carrying on a clandestine affair, would be careful too. But they also made the emails sound… false. Unlike Castle the spontaneous, the impulsive.

And that wasn't the only thing. She couldn't be quite sure to what extent this was herself seeing what she wanted to see but somehow, the emails just sounded… off. Reading them through now, something about them didn't sound quite… Castle-like and for a while she couldn't identify why. But then she did. It wasn't proof, nothing specific, except to her but it had the knot of desperate tension inside her, as if braced for a blow, beginning to unwind just a little. The words sounded romantic on the surface but the tone wasn't quite right.

Kate was, by now, very familiar with what Castle sounded like in a romantic relationship, the love notes he sent. And these emails lacked the… warmth she associated with messages from Castle. It didn't matter what he said; even when he teased her or texted her about case work, his messages somehow always had an underlying warmth, affection… and yes, love… in them. She couldn't explain it better than that and if anyone else had said such a thing, the old rational Beckett would likely have scoffed but somehow, it was true. They'd been having an ongoing conversation for the better part of four years now and with their new intimacy, his messages reflected that. She could always hear his voice in his messages to her, familiar with every nuance of his tones as she was.

And these emails… no, something about the voice of them wasn't right.

She needed something more solid. Esposito would never buy this sort of nebulous gut feeling. (In just about any other case, neither would she.)

Wait. Kate paused, backtracked. She'd reached the latter half of September. After Alexis had started at Columbia. But what about the day when Alexis had moved into her dorm room? She remembered the couple days before that. Castle had wanted to spend as much time as possible with Alexis so they hadn't seen much of each other then except in the precinct.

She checked, double-checked. There were no messages to Tessa on the day Alexis moved out. Or the day before or the day after (when she'd spent the day with him, attempting to comfort and distract him from his empty nest.)

Which would be consistent if Castle had written the messages and yet… It didn't fit the pattern. The other days when the man—the one who was not Castle—had been going to go silent because of his other commitments, he'd told Tessa about it, apologized, made reassurances, promises to make it up to her later. But those couple days, he hadn't. There was just the unexplained gap.

The dog that didn't bark. She abruptly remembered Castle referencing the Sherlock Holmes story, about the difficulty of making deductions from evidence that wasn't there.

It wasn't proof, not enough to convince anyone but herself, but it was an oddity.

A little energized, she went on, through September into October.

And then she found it. In early October. A short, brief message saying, See you tonight. I can't wait. Xoxo. Love, Rick. And rather more painfully, another message sent the next morning saying, Tessa, last night was amazing. Love, Rick.

A night which the other man had obviously spent with Tessa.

But that date. She remembered that date.

Her dad had returned from a brief business trip out of town and so she'd met up with him for brunch, even though it wasn't their usual weekend to meet up. Castle had joined them later—allowing him to briefly talk to her dad too (and even that short interaction had been enough to confirm that her dad and Castle were going to get along possibly too well for her own peace of mind since her dad was an endless font of stories about her younger self, many of which she'd prefer Castle never found out about.) And then she and Castle had spent the rest of the day and the night together.

Just to be sure, she hurriedly checked her calendar, confirming that, yes, that was the day she'd met up with her dad for brunch.

Castle had spent that night with her. There was no way whoever Tessa's mystery boyfriend had been could be Castle and this was proof.

It was one (or possibly two, including the other) slip-up but it was enough to cast doubt on every other message.

Castle hadn't done this. He hadn't written the emails and without that, he had no motive, nothing tying him to Tessa.

The alibi, as it were, for cheating on her would convince the boys, get them on her side, on Castle's side.

The murder would be harder but first, she had to get Castle out of jail. She needed her partner back and then they would get to the bottom of this.

Together, they would—could—do anything.

And then, when this was over, she would tell Castle she loved him (even though she believed he already knew) and she would spend the rest of the night, the rest of her life, living the truth she was sure of. Living the truth that she loved him and he loved her.

~The End~