Author's Note: Thank you for all the messages about the missing final chapter! I did post this on Halloween, but unfortunately FFNet has been having huge problems, so although this final chapter was supposedly available, most of you were unable to see it. :( I'm sorry about that! I'm reposting it today (Nov 6) in the hopes that things are fixed now and you'll finally be able to read it. Thanks so much for sticking with me. I hope you enjoy the end of the story!

If Castle had spent any time over the past year or so imagining what it would be like to be in Beckett's bedroom, this certainly wouldn't have been how he'd envisioned it: him standing in the doorway with Beckett's huge dog at his side, watching her prepare to perform a magic ritual.

But he didn't linger on that thought; he was too busy being fascinated by the whole process. The temptation to get out his little notebook and take some notes was powerful, but he knew Beckett would object, so he didn't.

Beckett had pulled an ancient wooden chest out of her closet, from which she had taken a variety of interesting items. In the dim light of the bedroom he couldn't see them very well, and his curiosity was driving him mad, but he didn't dare interrupt the proceedings.

So he just watched as Beckett used a thick piece of chalk to draw a circle on the floor, added a few mystical symbols around it, then placed candles at each of the cardinal points and positioned a few mysterious charms and crystals in other strategic places. Despite the fact that it had been ten years since she'd last done this spell, she showed no hesitation; she knew exactly what she was doing.

"Close the door," she said as she prepared to light the candles, and he hastened to obey, almost lightheaded with anticipation.

Was he really about to witness an honest-to-goodness magic ritual? And not just any ritual, but an actual summoning of an actual demon?

Holy shit.

He reached down to give Mickey another good scratch between the ears. The dog snuffled at him, nudging his legs affectionately. Taking a closer look, Rick could see why Beckett had been so worried about Mickey over the past few months; though still friendly and happy by nature, the dog looked tired, his vitality fading. Even the way he bumped his body into Rick's legs was weaker, unlike the previous times when the merest nudge had almost knocked Rick over.

Rick had high hopes, though, that all of that was about to change.

Beckett had finished lighting the candles and arranging her other items in their arcane patterns, and now she sat down on the floor just outside the circle. She crossed her legs underneath her and began to chant in a language he didn't recognize.

The low, mellow flow of her voice mesmerized Rick, lulling him into some kind of trance, his gaze fixed on the back of Kate's head.

Until suddenly she stopped chanting, and a whirlwind seemed to blow through the room. It ruffled the hair on Kate, Rick, and Mickey, made the curtains and wall hangings shiver, but somehow didn't blow out the candle flames, which continued to shine steadily.

When the breeze died out, Rick saw the demon standing in the middle of the circle.

It was smaller than he'd expected, that was his first irrelevant thought; somehow he'd thought it would be huge, larger than life (literally), but in fact it was smaller than Alexis. Yet a palpable air of evil emanated from it, Castle thought as he watched the creature strike an imperious pose and glare at Beckett.

"You dare presume to call upon me again, little witch!" Its mouth, full of sharp pointy teeth, curved in a sly grin. "You would like a trade, perhaps? Let the dog go, and you offer me your... friend in its place?" Its eyes flickered over to Rick and he shivered, feeling that inhuman gaze run across his skin like a physical sensation.

"Not gonna happen," Beckett snapped, using the full power of her cop-voice, which Rick had seen bring many a hardened criminal to heel. It didn't have quite the same effect on the demon, but Rick did get some satisfaction from seeing the evil creature recoil backward briefly.

"Yourself then!" the demon cried nastily, recovering itself, doing a quick two-step dance of glee. "I shall release the dog, and you shall be my gateway forever more!"

"No," Beckett said firmly. "I'm done making deals with you. This time, I'll tell you how this is going to go."

In the blink of an eye the demon went from pleased to furious. It hopped angrily from one foot to the other, shrieking.

"Evil little witch! You know not of what you speak! Release me!"

"Nope," Beckett said again. "But you know what I'm going to say, don't you? There was a loophole all along, and you probably didn't even realize it yourself." Her voice dripped with menace. "But you do now. You've already seen the mistake you made, the flaw in your plan."

"Silence! You know nothing!" the demon screeched, but she ignored it and kept going.

"You've been torturing me all this time, and you thought you'd step it up by making me live with the spirit of my mom's killer. But what you hadn't counted on was Mickey."

At the sound of his name, the dog gave a yip and moved forward, taking up his customary spot by Beckett's side. She leaned her shoulder against his and went on.

"Mickey always makes friends with everyone he meets, and when they're in his head, they have no secrets from him. Dick Coonan probably tried not to let Mickey know what he knew, but once he was in there, it wasn't up to him any more."

"Shut up," the demon hissed. Beckett laughed, low and sweet.

"No. Because this was the bargain we made: you give Mickey eternal life, and for my part, I was supposed to let him help me."

While she had been talking, Castle had edged his way slowly around the perimeter of the room, keeping as close to the wall as possible. Now positioned where he could see Beckett's profile, he felt a wicked grin spread across his own face when he saw her excitement, the way her eyes sparkled and her cheeks glowed with pleasure at finally having the upper hand.

"But you tricked me, of course," Beckett continued. "All this time I thought that 'letting him help me' meant that I had to live with this parade of criminals coming through my dog, let them use his body to get their work done. But that wasn't it at all, was it? It was just you playing games with me."

"The dog assisted you with your work," the demon protested, but they all knew it was feeble at best. And Beckett shook her head, brushing that off with a wave of her hand.

"That wasn't Mickey, it was the other souls you put in him. He was just the... conduit. But today?" She turned her head and briefly pressed her cheek against Mickey's. "Today, he really did help me. He told me who was responsible for my mom's death, and that's something I've needed more than anything, all these years."

The demon clapped its hands to its head as if to block out the words. "No, no, no. You misunderstand, stupid little witch. You are wrong."

"I'm not wrong!" she snapped. "And you know it. I figured it out - We figured it out," she corrected herself, looking over at Castle. He felt a wave of pride wash over him, and couldn't help the silly grin that spread across his face.

Beckett gave the tiniest of nods, and Castle took the cue; he stepped forward, picking up the thread.

"Dick Coonan didn't tell her who hired him," he said, looking down at the demon. "Mickey did. Mickey helped her, and that means she's fulfilled her part of the bargain. So now it's time for you to fulfill yours."

"You be silent!" the demon snarled at Castle. "I deal only with witches. I shall put a curse on-"

"You're not cursing anyone," Beckett interjected. She sat up straight, leaning forward again, pointing a commanding finger at the demon. "And he's right, it's time for you to uphold your end of our deal. You're going to give Mickey immortality - true immortality, not conditional. No more scumbag spirits parading in and out, putting demands on him, using him for their own needs. Just Mickey, his own soul in his own body. Forever."

"And you put him back to the age he was before," Castle added. He gulped as the demon turned its incendiary glare on him, but stood his ground, glaring right back.

"That's right," Beckett said to the demon. "You'll make Mickey the age he was before all this started, so he feels healthy, not old and weak. And you'll make him stay that way, forever."

"It will not be done!" the demon shrieked petulantly. "The bargain is not completed!"

"You lie," Beckett replied, cool as ice. "The bargain is completed, and you will do this. Then go away, and we'll never speak again. That's my final promise to you."

The demon snarled and spat, but Beckett calmly waited it out, and at last, stomping its feet, it shouted, "Very well! You win. It will be done."

At a gesture of its hand, Mickey stood up straighter; a shiver ran through his whole body, from head to tail and then back again.

And when it had passed, they could all immediately see that the dog was stronger again. He looked like the version of Mickey who had led Rick to Alexis, all those months ago. He looked big, healthy, and happy.

He wagged his tail vigorously and licked Beckett's cheek. She laughed out loud, a true, full-throated laugh - the first time Rick had heard her sound so truly free, and it made his heart leap.

"It is done," the demon sulked. "Release me, foul woman, and never shall we meet again."

"Sounds good to me," she answered. Leaning forward again, she swiped her hand through the chalk on the floor, breaking the circle. "Begone to whence you came," she declaimed, and just in case that wasn't clear enough, she added, "Go back to hell."

With a huff and a scream of impotent rage, the demon disappeared. A whirlwind blew through the room again, this time extinguishing all the candles and making the chalk swirl up into the air and dissolve.

Beckett wrapped her arms around Mickey and hugged him, hard.

Rick's mind was reeling from the whole experience, but he didn't want to intrude on the private moment, so he began inching around the room again, making his way toward the door.

But before he got there, Mickey wiggled free from Beckett's embrace and bounded over to Rick, nudging his head into Rick's thigh, nearly knocking him over once again. The dog's tail wagged furiously, and he smiled his doggy smile up into Rick's face and gave a loud, happy bark.

Castle couldn't help grinning. "Okay, Mickey, okay," he said, and leaned over to give the dog a good scratching. "What a good boy. How does it feel to be immortal for real, huh? Feels good, doesn't it?"

Beckett stood with a small smile, watching them. When Mickey broke away from Castle as well and went galloping out to the living room, she let out a laugh, shaking her head ruefully.

"He's like a puppy again," she said, her smile spreading across her whole face. "I never thought-" She paused, twisting her hands together.

"Castle, I couldn't have done this without you," she said more quietly. "Thank you."

"Oh, you could have, but it wouldn't have been as much fun," he quipped, drawing a smile out of her.

She gave a little snort of amusement, shaking her head. "Well, you're certainly right about that part."

"So..." He took a careful breath. "We're going to have to start investigating Senator Bracken, right?"

"Yeah." Beckett's humor dissolved as she pursed her lips, considering. "I don't really know much about him."

"Me either, but we will," he said confidently. "We'll find out everything there is to know about him."

"But we'll have to be careful - he's a powerful man. We can't let him find out that we're looking at him."

"Ooh, espionage," Rick enthused, bouncing on his toes. "This will be awesome. We should probably have code names."

She snorted and rolled her eyes. "Okay, well, consider that your first assignment."

Mickey came bounding back in, holding a tennis ball in his mouth. He dropped it at their feet and stood staring up at them expectantly, his tail whipping back and forth at top speed.

Beckett gave him a fond smile, then turned it toward Rick and said, "I think he needs a walk. Do you want to come along?"

At the word walk the dog gave an excited yip, grabbed the ball again, and raced to the front door.

Rick chuckled. It really was like having an enormous, fur-covered, extremely strong toddler. "Sure. I'd love to."

It had grown dark outside, but they walked to a tiny park near Beckett's apartment, and the two humans stood watching while the dog raced laps around the small scrap of grass, chasing his ball and cavorting happily.

"It's amazing," Beckett said for the dozenth time. "He's just so... free. I thought we were going to be stuck in that purgatory pattern forever."

"He earned this," Rick said. "The two of you earned it together."

"You helped a little bit too," she teased, nudging him with her shoulder. He smirked.

"Yeah, I did. I guess we make a pretty good team."

"We do," she agreed.

Kate lifted her head then, and their eyes met in the light of the full moon overhead. And there it was again, the now-almost-familiar sensation of electricity sizzling through him at the moment their gazes connected.

It felt stronger, more powerful this time than ever before. It felt like a thousand watts of energy plugged into him; it felt like bursting into flame.

Beckett's lips parted on an indrawn breath, her eyes widening, and he knew she had felt it too.

Reckless, Rick stepped closer, holding her gaze. "What the hell is that, anyway, Kate?"

"What is what?" she countered, but with a gleam in her eye that told him she was messing with him.

"You know what." He took another step, bringing him even closer still. "You've felt it too, every time. You pretended that you didn't, but you totally did. Tell me I'm wrong."

Kate tossed her head, flicking her hair back, but didn't break eye contact. "You're not wrong."

"I knew it," he exclaimed. "So, like I said, what is it?"

"I don't know, Castle," she murmured. "It must be magic."

And she leaned in closer and kissed him.

Thanks for reading, and Happy Halloween!