They had been researching for what felt like days now. Books, books and more books, the endless scribble of human language. Castiel would never understand why Metatron would want to flee with books. After days of reading, the scribbles started to look like black ants across the page. Obviously Sam thought so too since he had been taking more and more frequent breaks from reading. But Castiel never stopped, and he never would until they found something that useful.

They had found nothing useful so far though. There was nothing about how to cure a knight of hell, all any body wanted to do was kill one it seemed. This was probably because there had only been one holder of the Mark of Cain, so no one had ever needed the information that badly. Over the past few days, Castiel still hadn't been able to stop thinking of Dean, if he was human again, he was sure he would be having nightmares.

It seemed that Dean had been busy too, judging from all the dead bodies in the area. Every day a new report would come in on how yet another murderer had struck at yet another vegan bakery. Sam's computer was running now, a video from the crime scene, showing the dead bodies.

" The killer has struck again." The news reporter said "So far no one has any ideas what the killer looks like"

"And no one ever will." Sam remarked

"Yes, I do not think Dean would show himself to the cameras, even without a soul he wouldn't be that careless."

"Every time the killer strikes, it seems that they only kill the people with black hair and blue eyes, or people with light brown hair and hazel eyes." The news report continued, showing pictures of the dead bodies.

Sam sat up suddenly, "Wait those pictures look like us, is Dean practising on those people just so he can kill us?"

"It would seem so yes." Castiel said "It seems that Dean is testing the fact that he can kill replicas of us, so that when he does try to kill us, it will be without hesitation." Cas paused, " It will make him considerably more dangerous." They needed to find the cure, and quickly before more lives were lost. More importantly Dean needed to come back to Cas, his soul needed to come back, the one that had intrigued Castiel, it seemed like eons ago since Castiel had raised Dean from perdition. Since Dean had saved Castiel such a long time ago, Castiel needed to save Dean now. He had repeated that like a mantra to keep him going, he need to save Dean.

But now it seemed so hopeless. Castiel couldn't think about this anymore, he couldn't be alone in his head thinking about Dean. He couldn't do this anymore. In his anger and frustration he knocked the heaviest book off the shelf. But he didn't care.

"Cas what's wrong?" Sam asked looking

"Nothing, it doesn't-" A loud rumbling vibrated through the whole bunker.

"Whats happening?" Sam shouted over the noise

"I don't know! Maybe the bunker's collapsing?"

"Thats reassuring"

"Well thats surprising as its not supposed to-" Castiel's words were cut off yet again, (he seriously should learn to speak faster) as the rumbling suddenly stopped. The bookshelf seemed to have been replaced with an steel door. Cas tried the door, but unsurprisingly it was locked, so instead he used his strength and shoved the door harshly open.

"Do you think there may be something that could help Dean in there?"

"It's worth a shot." Sam shrugged. So Castiel led the way through the dark passage, noticing that along the walls there were warding placed against demons everywhere. It seemed that the information contained beyond the passage, was very precious. They kept walking for several minutes till they came to a brightly lit room.

The room had only one thing of importance it seemed. A sheet of paper lay across a table that had salt around it. Castiel tentatively opened the scroll, and read what was written.

"What is it? Will it help us?" Sam asked excitedly.

"Yes. It will help us." Cas slowly replied "It seems Cain's lover wanted to make Cain human again, and was looking for the same cure we are."

"Did she find it."

"Yes." In a manner of speaking, Castiel thought

"Then why didn't she use it?" Sam anxiously asked "Doesn't it work?"

"It does work. But it seems that she died before she able to get it, also I do not think that it would have been possible to get it at that exact time."

"Well then, what is it? Spit it out already Cas!"

Cas took a deep breath then turned around to face Sam.

"Its the blood of a former wielder of the First Blade. It seems we are going to have to pay Cain a visit."