The hapless Lawson family stood in a huddle in the kitchen as the tow strangers that they had invited into their home drew arcane markings on the floors and walls, and lined the smallest hole or crack with a layer of salt. Reggie Lawson watched the proceedings with narrowed eyes, his cold stare fixed on the back of Dean Winchester. Once again the man threatened to tear apart his family.

Dean, the walking apocalypse.

This ends here.

"Right." Dean said to the family, his tone implying that he was in charge. "Now you all stay here. Until we come back, don't leave the house."

"Cool." Monty's kid said brightly. "I've got a maths test tomorrow. I won't have to study."

"Don't think you're getting off that easily, young man." His mother said firmly.

"Where are you going?" Lawson demanded.

The brothers shared a glance, as if they knew what the other was thinking. Like they shared the same brain.

"We're going back to the base." Sam said. "Whatever's happening has got something to do with the way the Don was found."

"What, all those symbols?"

"Maybe." Sam hedged carefully. This Lawson was shrewd. He knew that something was happening that he probably wouldn't like very much. "But we really need you to stay put, okay? You'll be safe."

The other man's eyes narrowed, but he didn't reply.

Dean glanced back at the bewildered family, at the man that used to be his friend. "I'm sorry, man." He said, and his voice was thick with an emotion that Sam didn't often hear. His brother was genuinely apologetic. "I'm sorry about everything."

"So am I." Lawson said, his voice cold and strangely hollow-sounding. Dean flinched like he had been pricked with something sharp, before hustling Sam out the door to the Impala.

The car was momentarily caught up in traffic when Sam spoke.

"Are you going to tell me now?"

"Tell you what?" Dean looked at his brother sidelong.

"Whatever history's between you and Lawson that makes you become Mr Antisocial whenever you're put in a room with him for too long." Sam said. "You used to be best friends, until he just stopped hanging around with you."

"Used to be." His brother said faintly, as the Impala crept forward. Sam could tell that Dean was itching to slam his foot on the accelerator to avoid this moment altogether.

"Dean!"

"Alright!" He snapped back. "Dad shot his mom, alright?!"

Sam shot up in the passenger's seat, deadly straight. "What did you say?"

"You heard me." Dean said grimly. "I'd just turned sixteen, and Dad took me out on a hunt."

"I remember." He remembered sitting in the car the whole time and when Dead and Dad got back, their father was more morose than ever, and his normally unflappable brother was so distressed that even Sam's special brand of wheedling couldn't get anything out of him. "I remember that you and Dad wouldn't even look at each other until we were in the next state."

Dean nodded slowly, eyes still on the road in front of them and the structure of the base looming up at them from the ground like some sort of monster. "Dad had been on the trail of something burning the eyes out of its victim's heads." He said. "All the victims were teachers at this one school, and Lawson's mom was the school principal and had access to all these different things…" He trailed off.

"We followed her one night, and that was when she – changed."

Realisation slapped Sam across the face.

"Lawson's mother was a shape shifter?"

Another slow nod. "So he shot her." Dean said simply. "After, Dad broke into her office and stole a bunch of stuff out of her desk. It was only later – to late – when we realised that she was also investigating the deaths, 'cause she felt responsible since she was the school caretaker and crap. She was shifting and going undercover to – to find the person responsible."

"Dean, you're weaving a little to the middle of the road." Sam said gently. "It wasn't your fault."

"Yes it was. I saw her face. I recognised her. I could have got Dad to stop."

"You and I both know that once Dad got something into his head, there was no convincing him otherwise." Sam said sternly. "Did you get the one that was killing those people?"

"Dad found the clues in Mrs Lawson's notes and nailed him to the wall."

"How did Lawson find out?"

Dean shrugged. "I never bothered to ask."

Sam followed Dean into the enclosure, walking around the building and mingling with other recruits until they were out of sight.

"I've got to take a leak." Dean announced suddenly, when they were almost at the building in question.

"D-ean!" Sam protested. "If what Ruby said is true, we don't have time!"

"The apocalypse has waited this long. It can wait a little longer."

Sam reluctantly followed his brother into the deserted cafeteria. "Sam?" Dean asked.

"Yeah?"

Dean's eyes were shadowed as he turned to look at him. "I'm sorry." He said, and he felled his brother with a blow to the head. Sam fell limp. The guilt inside threatened to eat him up, but Dean managed to get a firm hold on his emotions and grabbed his brother under the arms and dragged him along the corridor to a supply cupboard. Moving the dead weight was quite a workout.

"Sorry, little brother. You'll thank me later."

"What the hell are you doing?"

Dean looked up. Lawson was standing in the cafeteria doorway, shock on his face. "Oh, hey. Give me a hand with this, will ya?"

Dumbly, Lawson did as he was bid and in a matter of minutes the two men had locked the larger Sam in the store cupboard. Lawson turned to Dean.

"Are you completely out of your tree?" He demanded.

"Most likely." Dean said dryly. "What about you? I told you to stay put."

Lawson's lip curled. "My wife and son are home, waiting for me to come back. We can't live like prisoners, Dean."

"You could get hurt. I don't want that."

"And I don't care. What if you can't do what you're trying to do? What does that mean for us then?"

Dan was silent.

"Do you even know what you're supposed to do?"

"I'm working on it, okay?" Dean sharply motioned Lawson to follow him, and the two proceeded to go to the Don's office, the place the poor man had been slaughtered for some demented ritual to bring back the bad of the bad, Samael.

Lawson reached the door first. There was surprise on his face and he was clearly wondering where the investigators had gone to, but when he pushed into the room, it was horrifically clear what the NCIS team's fate had been.

One wall was painted a dark red, and there by the door were the remains of the two agents who had remained at the crime scene. Dean swallowed as he looked at what remained. One corpse had been reduced to a dark ash through some intense heat, and deep gashes stared back at him from the second, where some wild beast had bitten down hard and twisted until flesh peeled clear away. Sickened, he looked away from the remains.

"Hell hounds and hellfire." He growled low in his throat. "It's happening. There must be something to stop it. Some ritual to use." Dean ran his fingers through his hair, wondering for a moment whether he had done the right thing, knocking Sam out. Yes, he decided, if Samael wanted Sam as a host, it was best that he wasn't here.

"Ritual?" Lawson sounded pissed. Beyond pissed, he was upset. "That's what's left of two people I've known for the last ten years! And you're worried about a ritual?"

"If I don't stop this, we'll all be dead." Dean snapped.

"And if you do stop this? Are you going to tell the families of the dead what happened?" Lawson challenged. At Dean's expression, he finished the question himself. "No, I didn't think so. That's why your family is always moving on to the next town, isn't it? So you won't have to deal with the consequences!"

Dean and Lawson, once childhood friends, stared at each other coldly, both refusing to back down. "I'm sorry." Dean said once again.

"You are not."

Dean turned away, frustrated. He'd never actually saved the world before, so this was all rather new to him. Dad, help me. He took a deep breath. "Can you hear that?" He asked, before the door was flung open once more and he and Lawson were staring face to face with the newcomers.

The man Dean didn't recognise at first, but the little blonde with her mussed hair and sharp eyes was terribly familiar.

"You're still alive!" Jo Harvelle sounded overjoyed, and before Dean really registered her appearance, she had flung her arms around Dean's neck and pulled him into a bone-cracking hug.

"Last time I looked, but you can never really tell these days." He said. "Jo."

"Yeah?"

"How the hell did you find me?"

She smiled brightly. "You should turn off your cell phone if you don't want to be traced."

Dean blinked. "You devious little witch."

"Thank you." The blonde turned, and offered her hand to Lawson. "Hi, I'm Jo, and this is Castiel. Jeez it's good to see you still alive, and where is-? There's this badass demon after you, wants to tear through to – and where is-?"

"How much caffeine have you consumed in the last twenty-four hours?" Dean asked curiously. "You're like the Energiser Bunny on a sugar high."

With some effort, Jo attempted to amp down. "This is Lawson." Dean said. "He's my normal friend."

"You have normal friends?"

"It has been known to happen."

"Excuse me." The rather nondescript man Jo was with interrupted. "While you both are chatting about how your day has been, the greatest evil any of us has ever seen is about to be birthed into this world to destroy the very fabric of this dimension as we know it."

"Do you want to repeat that? I kind of wandered into the middle there." Lawson's expression was torn between disbelief and amusement. He looked at the third man, and as soon as their eyes met, he looked down at the ground.

Castiel looked at Lawson for a long moment, thinking that he just saw something creeping below the surface. A flash of a face underneath the face. And then the moment passed and the human was human once more.

"Castiel." Dean looked up. His face was solemn. "I got your message. The one in my dreams."

The man looked up. His eyes narrowed slightly, but otherwise he gave no further clue that he knew what Dean was talking about. "And?" He said quietly.

"I know what to do." This time there was a tremor of fear in his voice, and Jo looked up at his face sharply. What she saw there shocked her. Dean Winchester was scared. "Tell me what to do."

Grimly, Castiel nodded.

"What are you going on about?" Lawson still had no clue what was happening. It was like he had been pushed on stage without knowing his lines, or even what the play was about.

"Dean, what's happening?" Jo repeated urgently.

Dean looked down at her. Dirt was streaked across her face, and blood. "I guess I owe you an explanation."

"And a lot more in between."

"For the past while," He said. "I've been having these – nightmares. I've seen the people I care about die, or become something that…"

"Dean?"

"Two demons were trying to make me do things. One of them wanted me to kill Sam, and the other wanted him left alive." Dean said bluntly. "Neither of them could possess me, so they got into my dreams. And he was there too. I… kept dying, and each time I saw Sam, and he asked me why I didn't stop it." He glanced at Castiel. "Which was his message."

"Which was what?"

Dean looked at her levelly, his eyes calm. "Castiel showed me that I could take Sam's place as Samael's host."

"What?"

"Jo, it makes sense. Sam's got the skinny on all these weird extracurricular supernatural abilities, and if this king demon or whatever he is gets Sam's body-"

"He will become invincible." Castiel finished.

"Good plan, up to the point where you get your ass killed." Jo said coolly. "So all this-" She glared accusingly at Castiel. "All your holier-than-thou companions, stopping to save me, and all the times I could have been killed watching you, this was all about getting Dean to the right spot so he could die?"

"No." Castiel said. "This was about getting you to the right spot so Dean could die."

Understanding, Dean reached into a pocket in his jacket and slowly pulled something out. It was the wickedly curving knife that used to belong to the demon Ruby. He took a deep breath. "You're the only one I can really trust here, even after how I treated you." He said. "Sam would never, and having him this close is dangerous anyway. I want you to do it." He offered her the knife.

"No."

"Don't you see? Sam's the chosen one, or whatever. I'm just… some guy. If he gets put in me, there's still a chace you can kill him." Dean's eyes bored into her. "I know you liked me once, and I'm begging you. If you feel anything for me at all now, you will kill this demon."

His voice was the bleakest and most solemn that Jo had ever heard coming from him. Reluctantly she reached for the blade, her hands brushing against his as he surrendered the knife to her. "You were never just some guy to me." She said quietly.

Dean very nearly backed out then. He tore his eyes from Jo and focused on the strange, urethral Castiel.

"Tell me how to summon Samael."

Castiel closed his eyes and bowed his head. "As you wish."

Dean laughed grimly. "You know I don't have a choice."

Castiel directed him to stand at the centre of the Seal, the All Seeing Eye looking down on him sombrely, waiting to funnel the entirety of its power through him, through his body.

The thought was terrifying.

"You're doing the right thing." Lawson said softly to Jo.

Jo Harvelle looked at him, and the slightly feral glint in her eyes was not that dissimilar the wild edge in Dean and Sam Winchester. "Maybe." She said flatly. "But I still feel like I'm about to take part in a murder."

"What now?" Dean stared back at Castiel, who still had his eyes closed.

"I can hear them." The fallen angel spoke softly. "The time of ascension swiftly approaches. My brothers move to head off Samael the moment he escapes the Final Seal. We must snatch his essence away from the Warriors of God the moment the demon steps forth, or your brother will be eternally damned and this world will be plunged into war of the kind it has not seen for a millennia."

"Will it work?"

"The demon's only choice would be to face my brothers while he is still little more than a thought form. He will come."

"Let's do it, then!"

"We must wait."

It seemed like hours, but when Jo looked at her watch, only a few minutes had passed. Then Castiel began to speak.

Dean looked up. The language was not Latin, or any other language he could identify or had heard before. He could tell immediately that it must have been a long-forgotten dialect, as literally only God knew how old Castiel was. The voice was smooth and hypnotic, and although Dean was still aware of all that was going on about him, he felt himself slipping into a trance. The room slowly faded out, as did the faces of Jo and Lawson, until the only thing in the dark was Castiel's voice.

And as Dean tuned into another form of awareness, the angel's words became clear.

"Behold the evil I see painted in my own reflection

The shadows of the dark places

Harken, lord of doom, master of death's dominion

As the Eternal Fool sprung from the clay and bone of the Great Enemy

I bid thee

Rise anew from the blood and ashes of this world

Samael, I summon you forth."