Dean knew he was in trouble the moment those blue eyes flashed black.

The demon was running his hands up Dean's sides, murmuring in his ear, eyes flashing between blue and black. His tongue snaked out to lick a line up the shell of Dean's ear and Dean shuddered, his hands finding purchase in the demon's raven black hair as he started to mouth at Dean's neck.

This isn't what he came here for, dammit. But this felt so good, and it had been awhile since he'd gotten this kind of attention from another person.

Not that demons are people, but whatever.

Sammy was dying. A hunting trip for vampires had gone wrong. Dean had expected to hunt down a cross roads demon and make a deal to save his little brother. What Dean wasn't expecting, though, was the demon to turn out to be so damn sexy with his stupid suit and devilish smirk.

The demon asked him what he wanted and Dean had told him. He was prepared to give up the rest of his life for ten short years with his brother. The demon just smirked and trailed his eyes over Dean, and said, "Instead of ten years, how about I let you live, under one condition."

Then he jumped Dean and was now ravishing him with his mouth.

The demon ducked his head down farther and nipped at Dean's color bone, eliciting a moan from the hunter. He was brought back to reality with the thought of the deal he still hadn't made.

"Woah, hold on," Dean breathed, pushing the demon away. The man frowned, but obliged, and stepped back.

"We didn't make a deal." Dean accused.

"Not officially, no."

". . . so what is the condition?"

"I thought I made it obvious."

Dean stayed silent.

"I want you, Dean."

Dean blinked.

"What?"

The man sighed and rolled his eyes.

"I want you as mine. As my mate."

Dean blinked again.

"Humans are so dense," the man shook his head, "Demons and Angels, the whole lot of the supernatural, mate for eternity and blah, blah, blah. I want you as my mate."

The hunter sputtered and looked incredulous.

"Why?"

The demon's smirk returned and he licked his lips, eyeing Dean once again.

"It's about time the King of Hell took a mate, and you're perfect to fit the part. All that self loathing and hatred you got going on there. . . mmmmm. Makes me tingle."

Dean's eyes widened and his mouth popped open in shock. King of hell? What?

"King of Hell? You're- you- wait- woah. No, no, no. How the fuck are you the King?"

The King in question shrugged. "I have special. . . . assets. And advantages."

"Like?"

The King paused and pursed his lips.

"My name is Castiel."

"Yeah, and my name is Dean. Nice to fucking meet you." Dean snarked, his eyes hard.

The demon rolled his eyes and tried again. "Dean, my name is Castiel. Think about it."

A bell went off in Dean's head. After years of countless research for hunts and thousands of books of lore, Dean had come a crossed the name numerous times.

"But that is an Angel's name."

"Bingo."

"You're telling me you're an Angel."

Castiel held up a finger. "No, I was an Angel. Past tense, love. I fell."

Realization hit Dean hard, and he swallowed.

"You fell with Lucifer."

"Pretty and smart. Again, you're perfect for me."

Dean didn't reply to that, instead, a bigger question came to mind.

"So, about the deal. Does this mean I have to live with you in Hell or. . . ?"

Castiel waved his hand and shook his head.

"No, you're free to live here on this meat bag ridden place all you want. Demons wont touch you, and neither will Angels for that matter. You will wear my mark, and no one dares to fuck with what is mine."

"And this is permanent?"

"When you die, you go to Hell with me."

"What about Sammy?"

Castiel huffed.

"You're brother will go to Heaven, you will still be able to see him. I wont let any harm come to you're brother. I swear on my eternal, damned life. Now, do you want him to live or not, love? Tick tock, time is running out for him."

Dean closed his eyes and weighed his options. Honestly, the only downside to this is that he will go to Hell when he dies, and it makes him shudder to think what will happen to his apparently "pure" (Angel's he has met have told him numerous times) soul down their. If he agrees, though, Sam will be okay and they can still see each other in death. Dean opened his eyes and stared into the painfully intense blue ones studying him expectantly.

"Deal."

A hand clamped over his shoulder, a brand mark appeared out of nowhere, and a ridiculously sly smile graced Castiel's features.

"Welcome to the rest of your life, baby." Castiel whispered, and slammed his mouth on Dean's.

Maybe this wouldn't be so bad after all.