Author's Note: Firstly, you guys are awesome. Secondly, here's the final installment. Apologies for the delay (my weekend was more eventful than I had anticipated), and I truly hope you enjoy it!

Disclaimer: This chapter contains Slightly Loopy!Beckett, who was far, far too much fun to write.

Detective Kate Beckett was having a very difficult time staying awake.

Objectively, she knew it didn't make sense. Her life was in very real danger—as was Castle's, for that matter, though he seemed to be holding up better than she was—and in all the previous instances she could think of in which her life had been in danger, she had been wide awake. Even if she'd been almost dead on her feet before disaster struck, mortal peril was an effective stimulant.

So here she was, over an hour spent locked in cold storage, and while she should have been climbing the walls, looking for a way out, all she wanted to do was nap. The exhaustion of their all-nighter had caught up with her (of course, she hadn't been tired then; they'd been too busy trying to save the world to consider the importance of a good night's sleep), and it was surprisingly comfortable in their little plastic fort. She still shivered—they both did—but with her hands tucked inside Castle's coat and her head tucked under his chin, she felt quite cozy. She could just drift off. It would be the easiest thing in the world.

"Don't you dare," Castle said, his voice shaking, just like the rest of him. It was almost like sitting in a massage chair.

Beckett gave a surprised start, though she doubted it stood out from the near-constant shivering she already had going on. "What?"

"Don't go to sleep."

Holy shit! How had he known? She almost laughed in her astonishment. Lowering her voice to a conspiratorial hush, she asked, "Did you just read my mind?"

Castle let out a little huff of frustration. "I didn't have to. You just said you were thinking about it."

"Oh." Beckett blinked. She didn't remember actually saying anything. Had she been thinking aloud without realizing it?

"Yes," he said testily, "you have."

His annoyance burned off some of the fog that had been weaving its way through her mind, and she frowned, her earlier near-giddiness gone. It was difficult to focus on anything anymore, but Castle was impossible to ignore. Even awash with fatigue and light-headedness, she knew—she was certain that she didn't want to upset him. Gritting her teeth, she shifted into a more upright position and rested her chin on his shoulder. If he wanted her to stay awake, then damn it, she would stay awake.

Still. "I'm so tired, Castle."

"I know." He didn't sound annoyed anymore, he just sounded sad, which was much worse, as far as Beckett was concerned. "Me, too."

"Hey, it's okay," she said soothingly, running her hands up and down his back. She had no idea what else she could say, she just wanted to make him feel better without resorting to outrageous lies. "It'll all be okay."

He sat up a bit. "You know, I think you're on to something with this back-rubbing thing."

"Hm?" She stopped, confused.

"The friction creates heat," he explained, rubbing her back more briskly than he had before and ultimately causing her sweatshirt to bunch up. "Damn," he muttered, and Beckett couldn't help but snort in amusement.

"My hero," she deadpanned. "Pull my sweatshirt back down; my back's getting cold."

"Actually," he said in a pensive, cautious tone that set off warning klaxons in her head, "would you be horribly offended if I put my hands under your sweatshirt? I'll keep them over your shirt. No funny business. It would be warmer for both of us."

Beckett shut her eyes briefly. "I'm still armed, Castle."

"And if I do anything inappropriate, you may shoot me."

She waited a few moments, giving him a chance to change his mind, and then sighed heavily. "Go ahead," she said, hoping her tone would adequately convey her lack of enthusiasm at the prospect.

Castle hesitated. "Really?"

"Just put your hands under my damn sweatshirt, Castle," she snapped, exasperated. "You're letting cold air in!"

"Sorry!" He hurriedly slipped one hand beneath her sweatshirt, using the other to tug down the hem. But when he tried to tuck his other hand beneath her sweatshirt, the hem was pushed back up.

"Castle…" Beckett warned through gritted teeth.

"I can fix it!" he insisted, plucking ineffectually at the soft interior of the fabric.

"'Warmer for both of us,' my ass," she grumbled, though she was having a hard time keeping a straight face. His desperate efforts to rectify the situation were hilarious, it was just the cold air whooshing up her back that wasn't amusing. Finally, she said, "I don't think you're going to be able to put them both in there."

He sighed. "I think you're right. Oh, well. I can alternate." He kept his left hand beneath her sweatshirt—it was cold enough that she was surprised he hadn't asked for inside-sweatshirt clearance sooner—and used the right to pull the hem down and hold it in place. "There. Better?"

Beckett gave a non-committal hum. It wasn't pleasant having his ice cube of a hand only one thin layer of fabric away from her skin, but she didn't want his hands to freeze, either. "What were you saying about back-rubbing?"

"Oh! Right." He cautiously tried it, his left hand sliding over the fabric of her shirt without bunching it. "Well, as I was saying, the friction creates heat, so that's good. Plus, it's a sort of non-verbal way to keep tabs. As long as my hand is moving, you'll know I haven't passed out or anything." He paused. "And vice versa."

Beckett let out a quiet snort. That explained it. "So you want me to rub your back to prove I'm awake, is what you're saying."

"I'm saying it would be a mutually beneficial exercise," he replied. "It'll make us both warmer, and if one of us stops, we'll know something's up." When she didn't immediately commence rubbing his back, he added, "At least I'm not asking you to recite poetry or name all the US Presidents in alphabetical order."

Cringing at the thought, Beckett begrudgingly moved her hands over his back, wondering how long she'd be able to keep it up before she cramped. "If this is so mutually beneficial, why do I have the distinct feeling that you owe me, Castle?"

"When we get out of here, I'll buy you dinner."

She smirked in spite of herself. "Shouldn't you have done that before you stuck your hand up my shirt?"

"Probably," he replied, "which is why I intend to make it up to you."

"If we get out of here," she said, more to herself than to him.

Castle only hesitated for a moment before insisting, "When." After a beat, he added, "After all, you can't die in here. It would be too ironic."

Beckett hummed thoughtfully. "I did always assume I'd take a bullet or something."

"No, I mean, you inspired a character named Heat," Castle said. "You can't freeze to death. The press would have a field day; it would be all over the papers."

Considering the prospect, Beckett winced. "Oh, god."

"Exactly! It would be front page news, and I know how you hate to make the front page." He sounded almost cheery. "And the headline would be a really obnoxious attempt at wordplay, like, 'IN THE BATTLE OF FIRE AND ICE, HEAT LOSES.' Don't give them the satisfaction."

"Well, when you put it that way…" Beckett sighed. "I guess I don't have any other option."

"That's the spirit."

She smiled briefly. It was good to hear him sounding happier. Sobering, she added, "You can't die in here, either."

"Oh?" he said inquiringly.

She knew he was just trying to keep the conversation going, or fish for compliments, or both. She knew he expected her to come up with something vaguely sarcastic and amusing, but her brain wouldn't cooperate. It just kept churning out depressing things she wouldn't have said for anything. Because I don't want Ryan or Esposito or the Captain to have to explain to Martha and Alexis that you were freezing to death while they were in a spa. Because if I make it out of here, it'll only be because you saved me, and I will not let you die for me, Castle. Because it's less without you—less fun, less interesting, less everything.

"You just can't, okay?" she finally said.

"That's not a very compelling reason—or a reason at all, really," he replied, though the warmth in his tone made her wonder if she'd been thinking aloud again. No, she was feeling a bit more clear-headed now than she had been before. She was ninety-eight percent positive she'd kept her thoughts to herself.

Still, she didn't want him to think she'd gone sappy. "I'll kick your ass," she said. "How's that for a compelling reason?"

"That works," came the hasty reply.

Making a small, satisfied noise—darn right—Beckett nuzzled her way back into the gap between Castle's neck and collar.

"No dozing," he said, voice stern.

"Hey, I'm doing you a favor," Beckett replied, her voice muffled but still clearly audible in their little enclosure. "You don't have a hood—or hair. I'm just sharing the wealth."

"I have hair," he objected. "Lots of it!" His hands twitched against her back, leaving her with the impression that he had really wanted to preen but had thought better of removing his hands from the relative warmth beneath her jacket. "Thick, manly hair," he finished sulkily.

"Not enough to cover your ears." She pointed out, shutting her eyes. "Your left ear will thank me for this. And then, in a few minutes, I'll switch sides." She smothered a yawn, distantly aware that she was close to dozing off and that doing so would be a Bad Thing To Do. She couldn't remember why, though; it seemed like a sound idea to her. Then Castle gave her back a particularly brisk rub, and she remembered. Biting back a groan of frustration, she upped her back-rubbing efforts.

"So," she said a few moments later, knowing that only conversation would keep her awake, "just what about this did you think would make for a good plot point?"

Castle paused. "Huh?"

"You said you researched hypothermia, but you never used it in any of your books."

"Ah. And you'd know, wouldn't you?" he asked, sounding almost smug.

She was too tired to banter. "Answer the question, Castle."

He let out a rather exaggerated sigh. "I don't think anything about this makes for good storytelling. Why force your characters to sit around and talk? There's no reason, unless there's something vital to the plot—or to the characters—that one or both of them are unwilling to discuss in casual conversation." Beckett's eyes snapped open and her arms stilled for a moment before she caught herself and hurriedly recommenced rubbing his back. To her private relief, Castle gave no indication that he'd noticed, but continued on apace: "And even if that was the case, there are less contrived ways to go about it. I was going to write about paradoxical clothing removal."

Beckett stilled again, blinking. "What?"

"Paradoxical clothing removal," he repeated. "It's a real thing. Sometimes, people suffering from hypothermia get so confused that they remove their own clothing. If they're found in that state, they can be mistaken for victims of assault. That's perfect mystery book fodder: something that looks like something completely different."

"Aha," Beckett said, pulling back for just long enough to move her head to his other shoulder and give his right ear the benefit of her comparative surplus of hair. "If I get to that point, I want you to take my weapon and put me out of my misery."

She had meant it as a joke and had assumed he would take it as one, but when Castle replied, he sounded troubled. "I wouldn't let you get to that point."

Beckett's arms slowed, and she realized with a little jolt of surprise that she was angry. Somehow, this particular brave insistence of his that everything would work out in the end—only the latest in a pretty long line—had unleashed a cold rush of fury inside of her.

She was angry that they were trapped here. Angry with herself, especially, for letting it happen (god, she'd felt like such an idiot when she'd heard the steel doors latch), and for being so tired—so physically and emotionally drained—that just giving up seemed like a viable, even attractive option.

And then there was Castle, his stupid, stubborn optimism like a goddamn spotlight illuminating her own cowardice and exhaustion. Every time he implied that they would make it out of there, she felt like a monster for silently disagreeing with him, even though she was certain hers was the more likely scenario. There had to be a point when hope ceased to be a good thing, when facing reality had to take precedence. There had to be. And while she was angry with herself for reaching that point, she was furious with him because he hadn't reached it, and he wouldn't. He would just leave her to wrestle with her private despair, and it didn't matter that his arms were around her, it didn't matter that his cheek was pressed against her hair, none of it mattered because there was just no more comfort to be had. Not with him on one side of an imaginary line and her on the other.

"Hey," Castle said, concerned, and for a moment Beckett was terrified that she'd been thinking aloud again. Then he asked, "Still with me?" and she realized that her arms had stopped moving.

For a horrible, selfish moment, she considered saying something like, 'Not really.' It would be true. But she couldn't do it; she wouldn't drag him down to her level just for the company. So she resumed rubbing his back, her arms sore and her hands beyond feeling, and said, "Still here, Castle."

He wasn't appeased. "Are you holding up okay?"

Beckett hesitated. She might not be able to emulate his positive attitude, but she dared to hope that she might be able to preserve it—or, at the very least, refrain from knocking great big holes in it. "About as well as can be expected," she said dryly, hoping that would be answer enough for him.

She felt his huff of laughter more than she heard it. "That bad, huh?"

Unwilling to elaborate, not least of all because she suspected he would know immediately if she lied, Beckett kept her mouth shut. Just drop it, Castle.

But of course, that was asking too much. "Beckett?" he prompted.

"Let it go, Castle." She'd meant it as an order, but it came out as more of a plea.

"I can't," he replied with a sort of cheerful bluntness. Sobering a little, he added, "Not even if I wanted to, Detective."

Exasperated, Beckett pulled away so she could look him in the eye and ask him… something. Plenty of questions presented themselves, chief among them: What the hell is that supposed to mean? But then she took in his expression, and any questions she might have had died in her throat. She didn't want answers. Not now, not when they were stuck in some goddamn freezer with only hours to live. No.

Castle was looking at her just as searchingly as she'd been looking at him. "Kate, I—"

"Castle…" she cut him off, almost desperate.

A faint, metallic clang startled both of them into silence. Turning her head towards the door—no more than a vague, rectangular blur through the plastic—Beckett held her breath.

"Did you hear—"

"Shut up, Castle."

"Okay."

Clang! This one was louder than the first.

"Someone's trying to get in," Castle said, his excitement evidently overriding his promise to shut up. "Is it the terrorists, do you think?"

"Who else would it be?" Beckett pulled her hands out from under Castle's coat. They were numb enough that they didn't even register the exposure to the colder air. She rubbed them together, wincing a little.

Castle watched her, worried. "What are you going to do?"

"Just stay still and be quiet," Beckett ordered. Castle looked mutinous, so she pressed a hand to his chest, both for leverage and as a silent reminder to keep his mouth shut. After another loud clang, the door began to open. Beckett reached for her gun with her free hand. She could see a pair of flashlight beams criss-crossing their way towards their ersatz tent. If she was going to make a move, she had to make it now.

She drew her gun… or tried to, at any rate. Her nerveless fingers fumbled the grip, and her arm—already stiff and sore—couldn't compensate for the error and instead continued the motion of drawing her weapon, though it remained in its holster. Her hand struck something, and then she was careening into the side of the plastic tent, carried by the force of her own momentum. The cone came down beneath her with a crumple and a crunch, and she landed awkwardly on her side, one leg stuck behind Castle and the other sprawled across his lap.

Two flashlight beams blinded her, and she heard Castle indignantly say, "You hit me!"

The beams moved away from her face, and she started scrambling for her gun again, blinking furiously in an attempt to clear her vision, until she was stopped by a familiar voice.

"Hey, easy, Beckett," Esposito said, and she slumped, almost overcome with relief. Someone knelt beside her, and after a few moments, her vision had cleared enough for her to make out the concerned expression of Detective Ryan as he helped her up. She had to lean on him heavily; her legs were no more cooperative than her hands had been.

"You guys okay?" Ryan asked, eyeing the wreckage of their tent with curiosity and what looked like the bare beginnings of amusement. Beckett's jaw tightened; Ryan and Esposito might be too concerned to comment right now, but she knew she was never going to live this down.

"We're fine," she said with more force than was probably necessary, and Ryan raised his free hand in playful appeasement.

"Speak for yourself," Castle retorted as Esposito hauled him to his feet. "You got me right in the nose."

Beckett suppressed an eye roll. "How did you guys find us?"

"Aren't you even going to apologize?" Castle asked, incredulous, before either of the detectives could respond. "It hurt!"

"How about we get out of this freezer?" Esposito suggested. "Then we can chat."

They made their way towards the door far more slowly than Beckett would have liked, though she knew she wasn't capable of anything faster than a toddle. From the looks of things, Castle wasn't, either. "Well, thank god it was you two and not the bad guys," he said, leaning on Esposito for support, "because that would have been a really embarrassing final showdown."

"Shut up, Castle," Beckett said, trying to get her stiff legs to cooperate.

"I'm just saying, you didn't even manage to get your gun out of its holster."

Beckett shook her head, too grateful for their improbable rescue to feel truly annoyed. "You want me to try again? I bet I could get it this time. And at least my last words wouldn't have been, 'you hit me,'" she added.

"Those are better last words than, 'oof,'" Castle replied.

"I did not say, 'oof.'"

Beside her, Ryan sighed. "I hate it when Mom and Dad fight."

It had been a cool night, and it was still far too early in the morning for things to have warmed up, but still, stepping out into the warehouse felt like sinking into a warm bath. Beckett pulled her hood down, allowing the air to work its way under her collar, and allowed herself a sigh of relief.

It didn't go unnoticed by Ryan. "How long were you guys in there?" he asked as Esposito spoke quietly into his radio.

"A couple of hours," Beckett guessed. "What time is it?"

Ryan checked his watch. "Just after five."

"Eleven hours until the bomb goes off," Castle said, looking grave. The van was nowhere to be seen. Turning to Esposito, who had wrapped up his radio conversation, he added, "We found the bomb, by the way."

"Yeah, we figured. We picked up trace amounts of radiation right around here," Esposito replied.

"Beckett's not the only one with cool toys," Ryan chimed in.

"There's a unit searching the warehouse. If it's still here, we'll find it."

An officer appeared with a pair of blankets in hand. Accepting one with a nod of thanks, Beckett wrapped it around herself with only a little help from Ryan. Her hands were still too far gone to function with anything close to normalcy. Similarly bundled, Castle said, "You still haven't explained how you found us."

"Alexis called," Esposito said. "She was worried—said you hadn't come home."

Beckett couldn't help but feel a pang of sympathy at Castle's troubled expression. "Alexis is supposed to be out of town," he said.

Esposito shrugged. "I guess she came back."

"We figured he was at your place, Beckett," Ryan said, seamlessly picking up the narrative, "but then Josh called and said you weren't home, either."

"Josh is in Haiti!" Castle objected before Beckett could do more than furrow her brow, thinking the same thing.

It was Ryan's turn to shrug. "I guess he came back, too."

Beckett looked down, surprised to feel herself blush. She was sure Castle was watching her, so she kept her eyes firmly fixed on the ground.

"Anyway," Ryan continued, "knowing you two, we figured you were probably out doing something stupid against orders." Beckett gave him a sharp glance, and he cringed. "And by 'stupid,' I, of course, meant…" he looked at the storage freezer, then adopted the expression of someone too polite to comment. "Never mind."

"So we sent patrols out to all the places we thought you might go, found your car, and searched the area until we noticed the light from the storage freezer," Esposito finished.

"Wow," Castle said after a moment of stunned silence.

Smiling faintly, Beckett gave Ryan a gentle bump with her shoulder. "Thanks, guys."

Ryan smiled back, and Esposito nodded at her. "There's an ambulance on the way. I figured you guys should get checked out. Don't want you losing any toes."

Beckett nodded, and Ryan gave her shoulder a brief squeeze. "Hey," he said, "think you guys can stand on your own for a few minutes?"

"I think we can just about manage that," she replied. Her legs were steadier, though she still couldn't feel her feet.

"Cool. If you start to fall over, yell or something." Ryan and Esposito moved a few yards away to speak to an officer who had, Beckett suspected, been hovering politely in the background for a few minutes. Castle stepped towards her, and by some unspoken agreement, they leaned against one another for support, shoulder to shoulder.

Castle poked one hand out from underneath his blanket to rub at his nose. "I rescind my dinner offer," he said with overblown offense. Beckett shook her head, knowing that while he was likely serious (or willing to be serious, at least), it had nothing to do with her hitting him. What she didn't know was whether she wanted to thank him for being such a goddamn gentleman, in his goofy, understated way, or whether she wanted to hit him again, on purpose. When had so many of his jokes stopped sounding like jokes and started sounding like opportunities to argue, or call him out?

Well, if was intended as bait, she wouldn't rise to it. "I'm sorry I hit you, Castle," she said instead. "It was an accident."

"Hmph," he said. Then, without any trace of levity, "The bomb isn't here."

"No, it's not." There would have been a fuss if the unit had found it, and in two hours, the terrorists could have taken the van anywhere. Still, they had more to go on than they had before—at least they knew it was in a white van. "But we found it once," she said bracingly. "We'll find it again."

"We will," he agreed, sounding more optimistic than he had a few moments ago, and she felt a small rush of pleasure at having bolstered his confidence. "Partners, right?" he asked, his light tone not quite masking a faint undercurrent of apprehension.

Beckett ducked her head, fighting back a smile of fond exasperation at his apparent need to even ask. After all they'd been through, some things should have been beyond doubt or question. Leaning against him, she lifted her head and listened to the sound of approaching sirens.

"Partners," she agreed.

Well, there you have it. Do let me know what you thought! I'm so needy!