A/N: This marks the final chapter of this story. Thank you so much to every person who has read, followed, favourited, and/or reviewed. Your response has been overwhelming. Special thanks again to Bec for being so wonderful about cowriting this. You've made this experience a delight.

PRESENT DAY

The drive home from the registry office was made in stunned silence.

Kate honestly had no idea what to say to him, so she kept her eyes fixed firmly on the road. The Vegas weekend, ditching Rogan, the fake wedding to the man whose name – whose face – she'd never quite been able to remember. Rick. All this time, it had been Rick. Her mind was a jumble, a swirling mess of questions. One and done, she'd once told Castle, and she barely suppressed the bewildered burst of laughter bubbling up within her as she recalled that scene in a child's playground, so long ago now. How was it was possible – through all these years – they had been married?

Castle spent the trip staring out the window, brow furrowed, occasionally turning to gape at her. Once, a strangled sound came out as if he were about to speak, but he closed his mouth with a snap, slumping back into his seat.

Likewise, they stood apart on the elevator ride up. She had no idea what was going through his mind. She barely had any idea about what was going through her own. Everything she had been through, every choice she had made in the past fifteen or so years now felt like it needed to be reevaluated in light of this new information, and she wasn't totally sure how to process it all.

She waited quietly as he unlocked the loft with shaking fingers, following him inside where they were greeted by the cheerful smiles of Martha and Alexis – whose grins were wiped off their faces at the sight of Castle's long one. Her own, too, probably.

He turned and looked at her, nonverbally communicating that he would follow her lead on how to handle this, excusing her if she needed to go process alone. Sweet, darling man.

But no matter how much a part of her longed to pull away, to sort through her raging emotions on her own, one look at his depressed face told her she was needed here more. He would excuse her and love her anyway, but right now, he needed her – and she needed him, too.

Partners.

Crossing the living room, she ignored the siren song of his office and the safety of their bedroom beyond, and instead dropped into one of the armchairs. Castle's surprised blue eyes tracked her movements, and she gave him the tiniest hint of a smile, inclining her head in invitation to him to join her.

He nearly tripped over his feet in his haste to be near her, perching on the armrest of her chair to face the questioning gaze of his mother and daughter together.

She leaned forward, burying her face in her hands.

"Dad? What's going on?" Alexis asked, guileless blue eyes darting between her father and his... was she really his wife already?

Castle's hand hovered at her back, seeking permission both to touch and speak. She glanced up at him, giving him another faint smile of permission. The comfort and safety of his caress eased her anxiety as his warm palm gently rubbed her back.

They would make it through this, and come out stronger for it.

"Well," he began, shaking his head in disbelief, "there's no easy way to say this, but... it turns out that Beckett and I are already married – and have been for fifteen? No, wait, '98... sixteen years."

"What? How?" Martha exclaimed as she and Alexis gathered nearer to hear the tale.

"I think I'm going to be sick," Kate murmured.

"You're already married?" Alexis gaped.

Kate looked up at the redhead. "Not really," she began, but her ever-loving fiancé interrupted her.

"Except we are," he confirmed. "The two of us met in Vegas, had too much to drink, and thought it would be a riot to take a cab to a drive-thru wedding chapel."

Martha stared at them both, an alarming combination of scandalized and entertained. "You didn't!"

Castle nodded glumly, yet there was a hint of pride in creeping into his voice. "We did."

"Yeah, we did, but I never thought that it was for real!" Kate defended herself. "You didn't either, if I recall correctly – it's all still a little hazy."

Castle heaved an overly dramatic sigh. He was beginning to enjoy himself. Bastard. "Yet we tied the knot."

She felt Martha's knowing eyes on her. "Does your father know about this?"

Oh, God.

"I really am going to be sick." She dropped her head into her hands and let out a low, pained moan.

Beside her, Castle shifted uncomfortably. "Do you think he'll be... angry?" he squeaked.

Her head jerked up, eyes narrowing as she glared at him. "If he is, it's deserved. I may not remember much from that night, but I do remember that it was you who convinced me Vegas weddings were fake!"

Castle gulped, staring down at her with wide, terrified eyes. "But everyone gets fake-married in Vegas! How was I supposed to know?"

Martha's voice cut in, smooth and just a little snarky. "It seems Richard has made a habit of eloping."

"Gram!" Alexis turned to her grandmother, horrified, as Castle dropped his face into his palm.

"I'm just saying that with his history..." Martha began, but cut herself off. "Don't worry, Richard, I'm sure Katherine will let you out of the doghouse eventually.

"But... what's going to happen with the wedding, then?" Alexis asked.

Kate placed a reassuring hand on Castle's knee. "You're not in the doghouse, Castle. I still want to go through with it."

His eyes lit up, all puppy-like eagerness. God, he's adorable. "You do?"

She nodded, and heard Martha and Alexis sigh with relief. Good. She was pleased she had made the right choice for them, too. "It feels right. I still want my day. In a sense, all this means is we don't have to worry about the legal side of things, because that's already taken care of."

He was nodding with renewed enthusiasm. "That's what I was thinking. If anyone gets particular about it, I figure we can call it an elaborate vows renewal."

She frowned at him. "Castle, beyond my dad and the people in this room, I don't want anyone knowing about it. Can you imagine Lanie's reaction? Or Esposito's? Or Ryan's?" She buried her head in her hands once more, as the other three murmured sympathy and agreement at the picture she painted.

Martha sprang up. "In that case, there's no more time for dilly-dallying. Alexis, you were working on that list of yours. You two need to finish packing for your honeymoon, and you probably won't get another chance," she said, shooing them into their bedroom before returning to her own tasks.

Castle took her hand and led her gently through his office to their bedroom, shutting the door behind them and guiding her to sit on the bed, where he perched gingerly beside her, refusing to let go of her hand.

"You sure you're okay with all of this?" he asked quietly.

She hesitated, but nodded. "I haven't really had a chance to process it, but the end result is still the same, right?"

"We still get to grow old together, if that's what you mean," he agreed.

She tilted her head and eyed him in confusion. "One thing I don't get, though, Castle. How did your marriage to Gina work if you and I have been married this whole time?"

His hand slid out of hers so he could run them both up his face and through his hair, before flopping backwards on the mattress with a groan. "That whole thing was a nightmare," he said, before peeking up at her. "You really want the whole story?"

She nodded, scooting across the mattress to join him, curling into his side and making herself comfortable.

He heaved a sigh. "Gina had been showing interest in me for a while. I don't say that to brag."

"Uh huh," Kate said, giving him a cheeky smile as she did so.

"It was the simple truth," he defended. "I got back from Vegas, where I'd just had the most amazing time with a mystery woman," he poked her ribs to make her squirm at that comment. "And I was feeling... I don't know... amazing and awful, all at once."

"Amazing because of me, I hope," she said softly.

He reached down and laced their hand together. "But awful, because you left, without a word, and I figured that magic like our weekend wasn't going to happen again any time soon."

"I'm sorry," she murmured. "I was young, stupid."

"You were young," he repeated, and then he paused, and turned to look at her with wide eyes that told her exactly what he was remembering. "You were—I took-" He let out a low groan of horror, and dropped his gaze. "Oh, God, Kate, I-"

"Yes," she said gently, squeezing his hand. "You were my first, but," she added, forcing him to meet her eyes, and giving him a warm smile. "You're now my last."

Her smile held firm, unwavering, and a matching one soon began to appear on his own face. "I can't help feel a little strange about that," he admitted.

"Don't worry, you'll get over that and the pride will kick in soon enough," she said with mirth in her tone. "Now, Gina?"

"Right," he said, shaking it off for now and getting back into the story, "So Gina was there and obviously interested and we made such a great team professionally that I thought why the hell not? We dated for maybe a year, and the next fall, I had a huge three month book tour around Europe.

Alexis came with us for a while, but when school started up again, we took her back to New York and left her with Mother and her then-husband. Hardest thing I've ever done. And after that, it was just Gina and me."

Kate nodded, and squeezed his hand again, listening, and supporting him through the tale.

"As we were going through Greece, we had a couple of major cancellations in the middle of all the chaos, so we just took off down to Egypt to see the pyramids and have a break for a few days, just the pair of us. It wasn't worth going all the way back to New York – we didn't want to upset Alexis by breaking her routine again, besides which we were starting to get snippy with each other because we working all the time but not spending any real time together. Long story short, we met some amazing people down there who convinced us we should get married. Gina had been trying to honor them by wearing their traditional head coverings, only to me that made her look even more gorgeous, and made envisioning her in a veil too easy. And what could be more exciting or romantic than eloping? So our friends there helped us marry, or, rather, have a civil ceremony, as foreigners can't actually marry in Egypt. They wanted proof of past divorces, so I asked my lawyer to fax through my proof of divorce from Meredith – he didn't even know to look for anything else, and obviously it didn't occur to me. Apparently that had been enough for the Egyptian clerk." He chuckled. "Only problem was, we were so swept away by the romance of it all that we never had the license authenticated. I guess we both assumed we'd done enough, and it was legal back home too."

Kate's lips parted in surprise. She would have thought Gina would have been all over those documents.

Castle noticed her look and said, "She'd never done anything impulsive like that before, and there was so much going on with the tour that we just announced that we had done it and leaked some photos to the press for publicity, and no one even questioned it. We didn't even question it, until things went downhill a few years later and Gina went to file for divorce only to find there was no record of our ever being married. Then lawyers got involved and everything was a little crazy in there for a while, but in the end I figured the honorable thing to do would be to pay her out as if we had been married legally, if only to make it all end quietly for Alexis' sake. Thankfully we managed to keep it out of the papers, just released a statement about irreconcilable differences. Anyhow, that's why Mother, in particular, but Alexis, too, is so happy to be a part of planning it all this time around. Neither of them found out until after it was done last time."

"That must have been tough for them," Kate murmured sympathetically.

"It was. That's why we're all so thankful we have you now. You fit with our family – you don't stand apart from it." He bent down to brush a kiss to her temple, and they lapsed into silence for a while. It wasn't long before Castle started fidgeting, though. "Kate?"

"Hmmm?"

"Have I been cheating on you all this time?" he asked timidly.

She raised herself up on one elbow so she could look him in the eye, curtaining them off from the rest of the world with her hair. "Some might say so, but in all honesty – did you have any idea that we were married before today?"

He shook his head.

"Do you think I had any idea?" she pressed.

He shook his head again.

"Have we already had the conversation about both of us having pasts, and both of us being okay with each others?"

He nodded vigorously, some of the light creeping back into his eyes.

"Has anything really changed, that we can do anything about now?"

He shook his head, laughter bubbling into his eyes. She felt an answering smile grow on her own face.

"I choose not to dwell on the mistakes of the past. The thing I care about most is that you're my future, and we're getting married in front of our friends and family, and we're going to build a life together," she said, leaning down to brush her mouth against his softly.

"Well said. I love you, Cadey-Kate Almost-Castle," he said with an impish grin.

She leaned away from him. "What did you just call me?!"

His blue eyes were wide and far too innocent. "The reason I never realized it was you is because I always thought the name of the girl I met in Vegas was Cadey. Now that I think of it though, that first interrogation, I was sure I'd seen you somewhere before. I knew there couldn't be two pairs of eyes as gorgeous as yours."

She clambered up onto her knees, still trying to process everything he was saying. "You thought my name was Cadey?!"

"Must have been Elvis' accent. Oooh, I still have our ring!" he said, scooting off the bed and crossing to his walk-in closet, where, after a moment of clattering about, he emerged triumphantly with a box Kate vaguely remembered was housed on a high shelf. It took him a moment to paw through the contents, but eventually he pulled out a box made of popsicle sticks with "DAD" painted on the top with a shaky child's hand, which, when opened, revealed a hoop earring.

Kate gasped, looking from it to him and back down to the earring again. Wait a moment, didn't she still have...? "Wait right there! Don't move!" she instructed breathlessly, leaping off the bed and opening her jewelry box, searching into the deepest depths. "Ah ha!" she cried out, turning to face him, palm openly displaying the twin of the earring in the popsicle box. "All I could remember was that your name started with R. I've been mentally calling you 'Rodger' this whole time," she explained.

With a kissably roguish smile, he lifted the earring out of the popsicle box, and took her left hand in his, letting it hover at the tip of her ring finger. "Well, Cadey-Kate Beckett-Almost-Castle, will you do me the honor of forgiving me for tricking you into a 'fake' wedding, and marry me for real this time?" he asked, sliding the earring onto her finger as she grinned.

She reached for his left hand. "Only if you'll do the same for me," she said, and slid the earring home, before reaching up to kiss him as thoroughly as she could.

It was some time before they remembered they were meant to be packing.

The End.