Dean was running.

The adrenaline was pumping through his veins as he ran through the halls of the bunker. The halls were dark, making it difficult to see.

Then he skidded to a stop when he found the door to his room. He shoved it open and scrambled to grab something from under his pillow. A silver blade glinted in the dim room.

He once again sprinted as he ran from the room. He turned a corner and stopped.

He had just been here. There was his room, the door still open.

"What the hell!" He was gasping for air now, but he rounded the corner again. He was right back where he started.

"Shit!"

There was a cold laugh that echoed on the walls of the bunker. "Oh no, no, no, no..." He was muttering now as he fidgeted and waited. He could feel his heart racing and the heat under his skin.

Waiting. It was horrible. The knot in his stomach tightened with each passing second. His eyes darted back and forth, anticipating what was to come.

Then he felt it. The air became oppressive and heavy, buzzing with energy. It was almost too hard to breathe. He spun around, blade at the ready.

A hand immediately grabbed his throat and pinned him to the wall. He dropped the blade as his head hit the wall with a crack and his vision faltered. He struggled against the unknown hands, as he fought for breath and his vision slowly returned. He was dizzy and disoriented, but he could see the dark brown hair and long coat. Then everything came into focus and he was met with sharp blue eyes.

"Cas!" He gasped, still fighting to breathe. A twisted smile appeared on the angel's face. "Oh no, Cas isn't home right now. He hasn't been here since you came back from Hell."

Lucifer tightened his grip. "And you didn't even notice. How sad. You must be a really good friend Dean." The angel grabbed Dean's arm with his free hand and twisted it with a snap.

Dean cried out as his bones broke loudly. His breath was taken from him as a fist smashed his face and he felt blood begin to trickle from his nose and mouth. Lucifer raised his hand again to hit him but he froze suddenly

An annoyed look crossed his face before he was able to strike Dean again.

"Now, now Cas. Let your big brother do his job." Dean stopped struggling as he realized what was happening.

"Cas!" He tried to speak through a mouthful of blood, "You can fight this, its okay."

"Really Dean, I expected more from you. I never thought of you as the begging type." Lucifer roughly grabbed his jacket and forced him to hang from the wall.

His arm burned with pain and Dean could feel tears welling in his eyes. "Cas please!" Lucifer just smiled and laughed as he threw him on the cold hard floor.

Dean coughed, the blood finally flowing free onto the floor. Lucifer slowly strode over to where he lay, relishing in Dean's agony. The archangel stood over him and Dean waited for the inevitable pain.

It came when the angel suddenly slammed a foot down on his broken arm. He cried out as the bones crunched against the stone floor. He tried to quite his moans of pain as Lucifer crouched down over him, his foot still on his arm.

"Now I can do this without little Sammy getting in the way. Let's see, what hurts more, here or here?" He raised his hand and spread it first on Dean's forehead then on his chest.

Both times made Dean burn and cry out. The pain was white hot and sharp, making his sight blur again. Lucifer kept his hand on Dean's chest and blood again bubbled from his lips. Dean felt like his heart was about to burst, his veins were popping and his whole face was red and contorted.

He made a last effort to grab Lucifer's hand and rip it off him, but the angel's hand stayed firm. "Oh don't worry. I won't kill you yet Dean. But this might sting a little."

There was an evil glint in his blue eyes, the ones Dean used to know so well. But then he faltered again.

The cruel smile dissipated and was replaced by a look of concentration. He began to shake and slowly retracted his hand. His face twisted and he grit his teeth. "No, no, NO!"

Lucifer staggered backwards moving away from Dean and staring at his shaking hands. Dean took the opportunity, scrambled to his feet and grabbed the blade.

Lucifer - Cas - whoever's eyes were starting to glow, Dean could almost see the inner turmoil within them, the battle for dominance within a single vessel.

Now it was Lucifer's turn to turn bright red. The effort to try and maintain control seemed to take its toll and he fell on his knees. Then the eyes looked up and met Dean's.

Cas's blue eyes met Dean's shining green ones and Dean's breath caught in his chest.

"Cas..." It was then with a pained expression that Cas finally said, "Run."

There was a blast of bright bluish light as grace flowed out of the vessel's mouth. The two streams of grace were intertwined, circling around each other, locked in battle. They were both light blue but one emitted a cooler presence while the other seemed red with rage. They continued to spiral and Dean watched for only a second before he began running in the opposite direction.

He ran and ran, ignoring the excruciating pain in his arm and the thoughts that were clouding his brain. Where was Sam, was Cas okay, how can he hide from an archangel?

He stopped when he could no longer breathe properly and his throat burned like fire.

He looked around. He was in the hallway with the door to the dungeon to his left. He went through it. He shut and locked the door behind him, like that would do any good.

He looked around clutching the angel blade still in his hands. What was he going to do? Cas could be dead for all he knew and he couldn't go to the entrance, Lucifer would expect that. He was trapped, down here in his own dungeon.

A sad laugh escaped him as he thought about it. He didn't know if Sam or Cas was okay and it was causing a lump to form in his throat. But they could be alive; he had to believe that, he was nothing without them.

Last he remembered before everything had gone to shit, was Sam calling out in warning. Dean had just figured it out, Cas wasn't Cas, Sam had been about to tell him but there was no need.

Before either of them could say anything Cas- no Lucifer had appeared behind him and had swung Dean around to face him. Sam had then jumped in and punched Lucifer in the face in an attempt to make him let go of his brother.

It worked. Lucifer was momentarily distracted and Dean took advantage and kicked him square in the chest. Lucifer was furious, he had stared at Dean like a cat with a mouse, hungry for his blood.

"Run Sammy go!" He had yelled before sprinting down the hall, praying that Lucifer was after him and not his brother. Apparently he was and that had led to his confrontation and broken arm.

But now, what would he do NOW.

His thoughts were wild, any idea was welcome. And them something came to him, something crazy, but it might work. He's not sure he liked the idea, what it would involve, but it was Cas. He could trust him couldn't he?

But he had said yes. Why? Why would he do that, maybe he shouldn't... But this was Cas, the Cas that had helped them through everything, that had helped him through everything but... No, no, no! Not now. This could be their one chance, if Cas was still alive.

He had to try.

He called out despite the burning in his lungs.

"Cas! CASTIEL!"

He could be giving himself away but he continued. He was praying to him now, he needed Cas to come to him.

Cas man please! I need you here, I need your help, PLEASE!

The air was suddenly filling with a soft light. A quite silence fell around the room and Dean found it surprisingly peaceful and calming.

The grace silently twisted through the air and Dean knew it was Cas, it just felt like Cas.

It swirled until it was hovering in front of Dean, condensing into a bright ball of light. It seemed to swim in graceful circles, closer and closer. It took Dean's breath away.

He didn't want to admit it to himself but he thought it was beautiful.

Dean, the familiar voice rang in his head, it wasn't the same as his vessel's voice but Dean recognized it.

"Cas." There was relief in his voice. He had escaped Lucifer, for now.

Dean knew he needed to talk fast but he struggled as he spoke the words. "Cas you need a vessel right?"

The light seemed to stiffen in response and the room turned slightly colder and dimmer.

Yes, it was a tentative response, almost a question.

"Then - I need - Cas - Oh godamnit! Cas I need you to possess me! Yes."

He couldn't believe that he said it, and it had left him breathless. He didn't like this idea but it was the only one he had.

The grace swirled quicker now and an oppressive atmosphere once again nearly suffocated him.

Dean, no I can't -

"Do it Cas! There's no time, it'll be easier for the both of us. We need to get out of here and I'm not sure I can on my own. But if you - uurrrg-" he didn't want to say it again, "if you do it, it's like two in one, we can both get out of here so just DO IT!"

Castiel still hesitated and floated around Dean until they both felt another presence.

The air started to buzz with heat and anger and they both knew who it was.

I'm sorry Dean, the voice echoed in his head before there is another blinding light and his whole body is lighting up like a holy fire.

It hurts. He is sure he is screaming but he can't hear over the sound of ringing in his head. It is several seconds before the pain stops.

There is no more light in the room, it is dark. But Dean can see.

His arm is healed and he assumes the rest of him is too, but he can't look. His body is not his own and he watches himself looks down at his hands without his instruction.

He can't control himself and it's scaring him. But then he realizes that something else feels different in his head. It's not just his mind he senses but also another's.

Cas? His thoughts are cautious as he pushes curiosity towards what he knows is Cas. Cas must sense his worry because he responds, It's okay Dean, I won't take advantage of you I promise.

Their private conversation is interrupted when the room of the dungeon blasts open. Castiel immediately readies himself with the blade that had still been in Dean's hand.

Lucifer walks in wearing Cas's vessel. Dean can sense the awkwardness Cas feels by staring at what had been him for so long. When Lucifer sees Cas he just stands and stares. Then he laughs.

"Oh so Dean thought he'd be smart did he? He let you use him as his meat suit?!" He sighs, "Well that'll just make it easier for me, you know. Kill two birds with one stone."

They begin to circle each other. Dean can feel his body moving, but the movement is different than his. It's tense and straighter, different from his usual relaxed lounging about.

"What's your game Lucifer?" His own gruff voice fills the room and it is him and yet not him. It's too monotone.

Dean is quite as he begins to watch the exchange.

"Game? There is no game here Castiel. It's simple, you, Sam, and Dean all threw me into the cage and do you know what kind of pain there is in there? The loneliness and torment? Of course you don't, but I'm just repaying the favor. I will make you all suffer."

Dean feels the power building up within him as Cas prepares to fight. Cas you know you can't beat him. We need to run! I know Dean I'm working on it.

Cas's eyes slowly scanned the room, looking for anything that might help in their escape. But he is subtle about it and makes sure not to lose sight of Lucifer for more than a couple seconds, keeping his head facing the archangel.

A jar. He sees a jar. He remembers it from when Lucifer had looked through the dungeon, and he remembers its contents.

The angels were still circling each other and Cas steps ever so slightly closer to the jar with each rotation.

When Cas is finally close enough, he moves with lightning speed.

When he reaches for the jar Lucifer is fast to react and is upon him the moment he moves.

Hands are on his neck again but Cas swings the jar forward and shatters it on the side of Lucifer's face.

He cried out as the holy oil started to burn through the skin of his vessel, bubbling and burning the borrowed flesh.

It was horrifying to watch, as he looked like Cas and it unnerved both Dean and Cas.

But Cas didn't waste any time and he threw the angel off him and ran through the door.

He was sprinting as fast as he could in his confined state towards the main entrance.

What about Sam!? Dean suddenly pressed. He's at the entrance.How do you know that?

Cas was silent as he continued on down the halls. Cas?! What happened?! Dean's fear was escalating with each step.

They finally reach the library and run through it to see Sam fallen on the stairs. Dean sees blood.

No, God please no! Dean can't tell if his thoughts are channeling to Cas, but he was starting to panic and he didn't necessarily want Cas to know what he was feeling at the moment.

He bent down to pick up Sam, a hand behind his back and the other under his legs. Although Sam was bigger than Cas at the moment, he lifted him with ease.

Heat and rage could once again be felt getting closer.

They strode through the door above the stairs, and rushed to get outside of the warding that surrounded the building.

Closer and closer, the air was crackling like lightening. Now Dean could sense Cas's panic and for the first time he felt that Cas was scared. He didn't know why it surprised him, considering that an archangel was on their heels, but he guessed he had always thought of Cas as the fearless warrior.

Four more steps…

Two more steps…

One more step…

Another bang alerted them that Lucifer was only a few feet behind them.

Cas stepped over the warding spun around to see exactly how close the archangel was.

He wasn't more than six feet in front of them. Cas gasped in surprise as Lucifer lunged forward to grab them, anger visibly red in his eyes.

Then the world spun and Dean felt himself lifted off his feet. He knew it couldn't have been more than a second, but it felt like an eternity floating in the space between dimensions.

Then his feet hit solid ground and Dean felt himself wobble as his body tried to compensate with the weight of Sam's body. Then he realized that he was panting.

Cas, are you okay? There was a pause before he answered.

Yes. I'm fine. I'm just still recovering.

From what Dean didn't know and he didn't ask. They were in a forest in God knows where. And Sam was lying on a pile of leaves.

Is he - ? Dean didn't want to think about it.

No.

Relief flooded him as Cas stretched out Dean's hand to rest two fingers to his brother's forehead.

Sam's eyes flew opened and he took in a sharp breath of air. The blood that had been on him was gone and his eyes were clear.

He looked around wildly before meeting his brother's green eyes.

"Dean!" He said, but then his brow furrowed as he continued to look at his brother.

It hurt a little as Dean saw Sam's expression change when he recognized that it wasn't him.

"Cas?" His surprise was evident in his voice.

"Hello Sam."

God, it felt weird that it was his voice speaking!

And he could see Sam's utter confusion. He had so many questions, he could tell by his expression.

"How – Why?"

"I no longer had a vessel. And Dean offered." It was short and brief, vague.

A few more seconds of starring before one of them spoke again.

"We should go. Maybe there is a hotel nearby." Cas said, "I think there is one a couple miles from here."

"Where is here – Dea – sorry, Cas?"

"We are in the red wood forests in California. I thought it would be a good idea to get as far away from Kansas as possible."

Sam merely nodded and Cas raised his hand again. "Wait Cas." The angel paused. "What happened, please tell me."

He sighed and lowered his hand. Dean felt how Cas stood up straighter than he usually did, and tilted his head in a way Dean never would.

"And how am I not dead?"

Cas starred at Sam and Sam fidgeted under the stare of his brother's green eyes.

"When Dean ran, Lucifer planned on killing you then and there Sam. He was going to with a snap of his fingers, but… I didn't let him. So he threw against the stairs instead and you were knocked unconscious."

"Thanks…" Sam said silently.

"After that Lucifer went after your brother. He found him and… he was very angry. I was trying to stop him, but as you know Sam it is hard to resist Lucifer. But I was eventually able to keep him away but Lucifer was very persistent. We both fought to keep control and it was becoming too much for my vessel. So I left and dragged Lucifer with me."

Sam continued to listen quietly and Cas went on.

"Then your brother ran, I told him to, but he insisted I come to him. When I got there he demanded that I –that I use him as my vessel. He said that way we could help us both escape easier. And indeed it did. But Lucifer must have returned to my old vessel and he came after us. I managed to get away and I came to get you Sam. From there I went outside of the bunker's warding and took us here."

"How is he?"

"Your brother is fine, he is very relieved that you are alive."

Sam gave a small smile, "Well tell him thank you."

"He hears you." Sam stood in silence another moment before asking another question.

"Cas, how long will Dean be your vessel?"

Dean's face fell as Cas refused to meet Sam's eyes.

"I don't know…"

"Okay…well let's go get a hotel room. We can figure things out in the morning."

Cas nodded and placed Dean's hand on Sam's shoulder. The world spun again but this time they landed in a motel parking lot. It was night time and the road was empty.

"I'll go get us a room." Sam walked off to the front of the building, leaving Cas and Dean alone in the lot.

Cas…

Yes, Dean…

How are you gonna find another vessel?

Just be honest with me Cas…

It will be hard to find another vessel that can contain me, not many can. You are the vessel of Michael, you are strong enough to hold me. It will be difficult to find an adequate vessel, let alone a willing vessel.

That was what Dean was afraid of.

And I would have to be careful; I am not liked by other angels, Dean. If I am spotted I doubt it would end well for me.

Dean didn't know what to think. He didn't want to be stuck like this. The only reason he had even considered this was because he trusted Cas not to throw him around like a rag doll. But he didn't think he'd be comfortable with having Cas in him for a long period of time. Cas could possibly read his thoughts, and he didn't like not having control of himself.

Dean must've been silent for too long as Cas said,

I don't have to stay, Dean. I can leave if you want me to. I won't force you to do anything, Dean, especially this.

But then you won't have a vessel…

Yes…

He couldn't abandon Cas, leave him vulnerable and without a vessel. Last time he had made Cas leave, he had got himself killed.

No Cas. We're not leaving you again, okay. We'll figure this out.

Dean could feel doubt filling his mind and he didn't know if it was his or Cas's.

Cas…

Yes…

Why did you do it?

Cas was silent.

Cas, why did you say yes?

Please, man.

I don't want to talk about it, Dean…

Fine…

Sam came back and unlocked the door to their room. They had nothing to bring in as the Impala was still at the bunker.

Sam crashed on his bed as soon as they walked in.

"I'm going to bed and you can do whatever angel's do. And tell Dean goodnight…"

Sam was out within minutes. Dean knew that Sam wanted to talk to him, to ask why, but they were all tired and Sam was still getting used to this new set up.

So how does this work, do I just keep to myself all night or…

You can sleep if you want, Dean.

How?

I can make you sleep if you'd like.

Okay, just don't do anything weird while I'm out…

I promise, Dean.

Okay…goodnight, Cas…

Goodnight, Dean…

Dean thoughts continued to trail on, thinking about how weird this was and what they were going to do.

He felt the soft push of drowsiness in his mind, that he knew was coming from Cas. He was grateful; his thoughts started to dim as his consciousness began to darken, until he fell into an unnatural sleep. His mind was filled with peaceful dreams, something he hadn't had in a long time and he rested throughout the night, comforted by the grace of the angel in his mind.