By the top of the stairs, Beckett was well and truly in cop mode. She held up her had for everyone to stop. If they barged straight in like her the Winchesters clearly wanted to, well they might have the element of surprise, but on the other hand they could be running straight into a trap. She peered cautiously around the door. At first glance, the room appeared empty. On the other side of the expanse of bare, worn carpet, the front door was open, still swinging slightly from a hurried exit. The carefully poured salt lines were scattered, as though a wind had struck up inside the house and disrupted them. Two windows were broken and the vomit-green wallpaper had new tears in it, where rock salt been embedded in the wall by a shotgun blast. There was no-one in the room. She stepped around the door, signalling that it was safe.

There was a smear of blood on the wall beside the door into the kitchen. Her breath caught and she steeled herself. Please don't be Ryan or Esposito. Please don't be Ryan or Esposito.

"Stay here," Sam Winchester instructed, blocking off her path with an arm before she could bring herself to step through the door.

Being ordered to stay where she was by someone, particularly if it was in order to protect her feminine sensibilities would usually annoy Beckett, making her automatically want to take charge of the situation, but this time she knew she was less capable of taking care of the situation if there was a demon in there. It was better to let the professional go first. But if Ryan and Esposito were in there, hurt, she wasn't going to wait outside and let Sam deal with it.

Sam stepped through the door into the kitchen. Beckett forced herself to stand still and wait for him to give the okay.

A second later, there was an almighty crash, followed by a thumping. Beckett readied her shotgun, peering around the door. The kitchen was empty of furniture, just a bare room decorated in orange and brown, with spaces between the cupboards where the fridge and oven would be. A plastic-topped breakfast bar divided the room into two. The thumping had been Sam being thrown over it, hitting the stools that were built into the floor on the way down and finally landing heavily on the unconscious body of a well-dressed Asian man. Beckett breathed a sigh of relief that it wasn't Ryan or Esposito, and then mentally berated herself for being so insensitive. Even if he wasn't her friend, he was still a person. At least he was breathing.

"Sorry," Sam whispered to the unresponsive figure as he rolled off him, reaching for the knife that had tumbled from his hand in the fall.

The demon who had thrown Sam across the room rounded the end of the bench to finish Sam off and was taken by surprise when Sam suddenly threw himself forward, knife in hand. The two tumbled away into the far section of the kitchen. Beckett dashed forward as quietly and inconspicuously as she could and began to check on the unconscious man. She used her police first aid training to ensure he wasn't going to choke on his tongue before checking his spine for damage. The only injury she could find was a large bump on his head, so she dragged him out of the room, out of the way of Sam and the demon.

When she had him in the living room she could hear the sounds of the recorded exorcism playing in the first bedroom, interrupted by shouting and taunts from Dean and a woman with a somewhat shrill voice. Still further crashing was coming from the next room. Beckett made a judgement call and decided she would be of more use helping Sam in the kitchen. She picked up her salt gun and marched back into the kitchen. It was just as well she did, too. Sam had clearly been holding his own. The demon was bleeding heavily from a cut on its leg, blood staining its torn jeans red. Its black eyes were stark against a pale face marred by bruising, and its right arm was bent at an unnatural angle. But Sam had lost the knife. It was halfway across the room, its tip embedded in brown linoleum and probably the floor beneath. Sam was against the wall, grabbing at his throat, held there by some kind of invisible force. He gasped for breath, his face turning red.

The demon was in the middle of one of those acid, evil-mastermind speeches they seemed so fond of, its attention fully on Sam. "You can make this stop," it was saying, "All you have to do it say yes."

"No," Sam gasped out, subtly catching Beckett's eye and glancing over at the knife.

Beckett checked that the demon was concentrating on Sam and snuck over to the knife. She pulled it out with one hard yank, as Sam did his best to distract the demon with any insults he could get out. The knife was lighter than she had expected, worn down by use. It felt big and clumsy in her hand, made for someone much bigger than her. She stood up, saw the demon catch sight of her out of the corner of its eye, and leapt forward, stabbing it in the back with one quick, sharp thrust. It went in shockingly easily, and the demon burnt out with a red-white light and a crackle. The body it had been wearing collapsed to the floor, dead, the knife still in its back. Beckett stood still, trembling, as Sam pushed himself away from the wall, coughing as he recovered the ability to breathe. The room smelled of sulfur.

"He was already dead," Sam assured her as he pulled the knife from the dead man's back.

It didn't make her feel better. It was a sickening thing, stabbing someone, even if it was to save a life. Much worse than shooting someone. It was somehow more personal. Her mind kept replaying the squelch of the knife entering his body and her stomach churned. There was fresh blood on her hands.

Sam casually wiped the bloody knife on his shirt and examined it for damage. Beckett hoped she never got that used to killing things. She followed him out of the room to see if the others needed help.

They found them in the second bedroom. There was a dead man on the floor in front of the doorway. They had to step around him to go in. Inside, two women were lying in the corner, torn up and unconscious. Someone had carefully put them in the recovery position. A young man was stirring on the other side of the room.

In the corner beside the closet, Dean Winchester was sitting on the floor, leaning against the wall, clutching his stomach. He was even more covered in blood than he had been after they had exploded the demon in the basement. Castiel was crouched beside him, trench coat ruffled and hair even messier than usual, but otherwise clean and unharmed.

"Dean!" Sam exclaimed, crossing the room in three long strides.

"Fireworks," Dean said clearly.

Castle came across from where he had been examining the closet door to stand beside Beckett. He took her in his arms and hugged her briefly. Beckett hugged him back, ignoring the stickiness of drying blood on their clothing, choosing to concentrate on the comforting warmth of Castle's body.

"Any sign of Ryan and Esposito?" She asked, half dreading the answer.

"We… uh… found a gun and a crushed IPod," Castle told her, "No other sign though. They're probably hiding somewhere."

Beckett nodded. Well, at least they hadn't found their bodies.

"There are no fireworks, Dean," Castiel was informing his friend, "I must examine your wound."

"Want to check out my body, huh?" Dean sounded tired, but managed a grin.

"Dean! Let us look, you could be hurt really bad," his brother demanded, almost shoving Castiel out of the way.

"What happened?" Beckett asked.

Castle grimaced. "I was facing the other way, shooting this demon with rock salt, only I had to use my left hand," he waved his cast, "And when I finally got it and turned back around, another one had slit open his belly. It was so deep…" Castle trailed off, a look of faint horror on his face as he remembered. "I finally got them into the devil's trap, but I swear he stopped breathing. I thought he was dead. By the time Castiel got here and disposed of the demons, Dean was okay again."

Beckett followed his gaze over to where Sam and Castiel were examining Dean's abdomen. Sam was prodding at a cut. Dean groaned. "This is going to need stitches," Sam said, removing his shirt to rip into bandages.

"Well, less dead, anyway," Castle amended.

"If I ever die in your company, I want someone else to check that I'm dead before they put me in the coffin."

"I will take him back to Detective Beckett's apartment," Cas told Sam.

"Wait," Dean held up a hand, "What about Ryan and Esposito? I like those guys."

There was a muffled banging from the closet.

"I knew there was something in there," Castle said.

Beckett followed him over to it, ready with her gun in case it wasn't Ryan or Esposito. Castle flung the door open.

"Are you holding hands?" He asked amusedly.

"No," Ryan and Esposito denied in unison, dropping hands.

Esposito stepped over the line of salt he and his partner had laid on the inside of the door first. His shirt was torn and he had the beginnings of a black eye, but otherwise he seemed fine. He carried a small, half empty bag of salt.

"There were too many of them. We lost all of our weapons," he said. "Sorry we couldn't hold them off longer."

"You did well for beginners. We probably put a bit much on your plates," Sam said, throwing them a quick once over before turning back to his brother. "See, they're fine. Now will you let Cas take you?"

Ryan followed Esposito out of the closet. A line trail of blood ran down his face from a cut on his forehead. He was limping slightly. "What kind of house doesn't put doorknobs on the inside of closets? We could have been stuck in there for years."

XXX

An hour later, they were back in Beckett's apartment. They stopped and called emergency services anonymously from a public telephone on the way, and followed it up with a quick pause in the backyard of an unoccupied house to hose themselves off. There was no way they could walk up to Beckett's house covered in that much blood without being noticed. Anyway, Beckett wanted nothing more than to get the gunk off her as soon as possible. She felt a little sick every time she thought about being covered in person.

Dean was in her bed again, scrubbed clean and thankfully not naked this time. Beckett thought Castle might be frowning a little jealously at when he saw where Dean was, and realised that no matter how gorgeous Dean might be, it gave her way more of a thrill to think of Castle being jealous than it did to think of doing anything with Dean. She kind of thought she'd have some serious competition if she'd tried anything with Dean anyway, what with the way Cas was looking at him.

"Is anyone else hungry?" Castle asked. Beckett looked out the window. The sun was coming up.

They took turns in the shower before ordering food. Beckett had never felt anything as good as the warm water as it ran over her, and the feeling of clean, non-matted hair. By the time she got out, Dean was out of bed, sitting on the sofa. A thick white bandage was wound around his middle, and a red scar in the shape of a handprint stood out vividly on his left shoulder. Cas was gone, checking out the demon situation and getting food. Beckett sat next to Dean. Castle pulled up a chair to talk to Dean.

"So what do we do now that we know about these things?" Castle asked, "I mean we can't just go back to how we were."

"Yes you can," Dean said firmly, "Someone needs to deal with the humans. They're not going to stop killing each other just because it's the apocalypse. In fact it's probably going to get worse. And you," he turned to Castle, "Keep writing. It makes people happy. Distracts them from reality." A faraway, unhappy look appeared in his eyes for a moment. Something told Beckett that sometimes Dean needed distracting. Then it was gone and Dean was grinning at them. "And I want to know what happens to Nikki Heat."

XXX

They sat around eating and napping and generally recovering for most of the morning. Castiel popped out periodically to check on the situation, and finally gave them the all clear just before noon.

It was kind of awkward saying good-bye. What do you say to people who you just fought demons with and will probably never see again? Don't worry, you got this? You can totally stop the world ending? In the end, Beckett just went for "Goodbye," and promised to call Bobby Singer if she ever comes across a case that might be supernatural, rather than taking it on herself.

Ryan and Esposito disappeared shortly after the Winchesters, promising to check in later. Castle made a phone call to Alexis and Martha. Beckett could almost hear the relief and anger coming through the phone, even though she'd gone into the next room to give him some privacy.

"Come to my place for lunch," Castle insisted when he came back into the room. "They were worried about you too."

He wouldn't let her decline, but in the end she was glad she didn't. When Alexis greeted her with a hug almost as long as the one she gave her father, Beckett suddenly remembered how good it felt to know people cared about her.

XXX

"So," Castle said after lunch, when Martha and Alexis had left the room not-so-subtly to give them some time alone together. "Demons are real. I bet you fifty bucks that the next time I suggest the CIA it's true."

"A hundred."

Beckett smiled, moving in a bit closer on the couch.

THE END

AN: I hope everyone enjoyed it. Thanks for reading and reviewing. Next up, I'm working on the SPN boys in New Zealand for the SPN around the world challenge. There may also be some continuation of my SPN/Harry Potter crossover, depending if I get time.