Sam learned that angels really exist when one appeared to him in Hell. He heard higher level demons speak about them in hushed tones, calling them divine beings of light, and other less than kind things, but never saying the word. Sam had always just assumed that they were talking about angels, but had always been too busy to really follow up. The angel was looking for Dean to 'raise him from perdition', and Sam had to inform him that he was a little late on the curb. The King would soon learn, that was just the angel speaking in code, saying what his superiors wanted to hear before slipping Sam a note. Normally, Sam would have assumed it was a trap, that the location on the note would be warded to trap him as soon as he entered. But Sam had been intrigued by the blue-eyed angel and went alone so as to be less conspicuous. Well, mostly alone. Dean was human, and therefore hard to ward against.

Sam entered the building and halted for a moment at the symbols on the walls. Dean stopped just in time to keep from bumping into his giant of a brother.

"Sam, what the Hell?" Dean hissed. Sam realized that Dean was human, he couldn't see the writing on the walls. It took Sam another moment to process that the symbols were not to keep him in; they were made to keep other angels out. His shoulders relaxed minutely and he kept walking, a grumbling but alert Dean behind him.

"King of Hell,"

"Angel. I never did catch your name," Sam said, trying to keep the awe out of his voice. He had always been religious, never really stopped, even as the King of Hell. He kept his voice cool, but not disrespectful. Dean, however, did not.

"Are you even sure this is a real angel, Sam?" He demanded. The angel turned piercing blue eyes on him. Lightning flashed unexpectedly, no source in sight, illuminating the angel as he spread the shadow of wings. Sam didn't flinch, even though he wanted to, expecting the angel to try and smite Dean for his disrespect.

"My name is Castiel, and I am an angel of the Lord." He said with a voice that sounded like he had been gargling gravel. The lightning disappeared, and with it, the wings.

"Why did you request this meeting, Castiel?" Sam asked before Dean could say something else that would get him smited for real this time. Sure, Sam would defend his brother to the death, even against an angel, but that didn't mean he wanted to if it could be avoided.

"That is a long story." He said. "But I will start at the beginning. God created angels and heaven, but he wanted to make more. Creatures with free will. So he created Earth and humans. Not all of the angels were happy about gods newest creation, especially the brightest of us all, the Morning Star. You know him as Lucifer. God cast him down for his hate of humans and the creation of demons and Hell. He ordered that his most loyal son, Michael, cast him into a cage in Hell. This cage could only be unlocked by breaking 66 of the 666 seals on Lucifer cage. After he had ordered Lucifer's banishment, God disappeared and hasn't been seen by any angels to this day. Soon after God left, the archangel Gabriel also disappeared, and Michael was left in charge of heaven."

"That's a nice story, but what's with the Bible lesson?" Dean snarked, admittedly a little freaked out.

"You being sent to hell was supposed to be the first seal." The angel said bluntly. Dean blanched, but Castiel continued, apparently oblivious to the human's reaction. "Well, you breaking was the first seal. The Boy With The Demon Blood prevented that."

"That's why you came to rescue me," Dean said.

"No," Castiel said, and Dean sputtered for a moment. "I was supposed to rescue you after you broke, shed blood in Hell."

"Wh-what? Why?" Dean asked, thrown for a loop. Angels were good right?

"Because Heaven wants the apocalypse to happen as it is destined. That's why I'm here. I want to stop it."

"You want to go against Heaven?" Sam asked incredulously. Castiel nodded stiffly, looking uncomfortable yet determined.

"Yes. Once I discovered their true intentions, I realized that I don't want the end of humanity. They tried… less than savory methods to change my opinion, and I pretended it worked."

"And you decided to come to the king of Hell because…?"

"Because you are the only two beings that can stop fate from falling over the precipice into utter chaos and death." He said solemnly.

"How?"

"You are the vessels. The true vessels, meant to contain Lucifer and Michael for the final battle." Sam's eyes widened and he took an involuntary step back. Sure, he was the king of Hell, but he didn't consider himself evil. Becoming the actual Devil was a whole other level. Maybe he wasn't strictly good, but he wasn't that bad.

"You… what?" Dean asked, still trying to grasp it.

"You are Michael's sword."

"Oh, that is just fan-fuckin'-tastic. So that makes Sam… no. Oh Hell no." Dean said, his protective instinct flaring at the thought of Lucifer wearing his little brother to prom. Sam looked a little numb.

"Heaven doesn't know about you rebelling, correct?" Sam asked, focusing on the task at hand instead of dwelling on the fact that he was apparently the Devil. Castiel nodded. "Then we have someone on the inside. Report back to your superiors as normal and report back to us when you can." Castiel just blinked before nodding at the sudden command. He knew how to take odors, after all. He hadn't expected anything less than a commander from what he had heard about the King of Hell. Castiel was about to leave before Sam said, "Cas? Be careful."

The angel's eyebrows furrowed slightly as he nodded. He sounded sincere about the being careful part, and the angel couldn't help but wonder why. He cleared his mind of those thoughts before returning to Heaven. After all, he had agreed to be careful, and it would not do to be caught.