Hello, everyone! This is my second Supernatural fic. I did this one for a friend, and, though, I don't personally ship Destiel, my friend does and requested this. I'm not good with romance, but I did it anyway.

Enjoy! :)

The blade shook vigorously in his hand. His fingers twitched as they held it with a firm, white-knuckled grip. It wasn't rage. Oh, no. He was far past rage. He was at a crossroad of indifference and pure blood-lust. His muscles itched and ached, begging him to swing that blade. His very blood pulsated with a murderous calm.

His gaze rose from his blade and rested on the figure in front of him. The angel. Somewhere, he knew this was wrong. He knew that he shouldn't do this. This angel, wasn't it his friend? But, this voice of conscience was drowned out by his craving for bloodshed. He didn't care. Oh, how he didn't care. No, he had never cared less about anything. This wasn't anything important. This was one insignificant angel, pathetic, worthy of death. This was just prey. And, you know what predators do to prey.

He took one step forward, then another. Then, quicker than lightning, he was there, right in front of the angel, his hand holding the blade directly above the poor victim's neck.

"Dean," it spoke. "Dean, you have to stop!"

But, he was far from stopping. He couldn't stop even if he wanted to.

Delicately, he ran the blade just over the angel's neck, creating a small trickle of blood.

The angel pushed against him, trying to keep him away. "Dean, listen to me! You need to control yourself!" He yelled. All of his cries of disapproval fell upon deaf ears, as Dean quickly shoved him back against a wall, grasping his neck with the blade poised above his chest. The only thing keeping him from plunging it into the Angel was the pleasure of seeing poor Castiel struggle.

"Stop, Dean! Please!" The angel said, with his hands around the ones on his neck, trying to pull them away. "Don't do this."

Dean almost smiled at the scene before him. It was a malicious smile of murderous lust. He was powerful. The benevolent calm that the blade had washed over him gave him this strength. The strength to take down thousands of angels like this one. He could tear their vessels apart along with their very souls. And he would never have to worry about their return because, after all, where do angels go when they die?

The blade slammed into the angel's stomach, impaling through the skin and innards. The lethal wound began to glow with the panic-filled light of an angel's death. The First Blade twisted to the side, adding to Castiel's agony. Dean's Mark glowed in pleasure and desire. It craved more.

Castiel let out a pained yell and his hands went to his abdomen.

Dean pulled the now bloodied blade out of the angel's body. The angel gave what almost sounded like a sigh of relief when the blade was removed from inside him. But the relief didn't last long once death began to run its course.

Castiel closed his eyes, not wanting to look at Dean, not wanting to remember him like this. Of course, he knew it was the Mark. He knew this wasn't the real Dean. If he was to die, he would remember the old Dean, not who he had become.

The murderous man glanced at the red liquid dripping from the knife and streaming from the wound. His animalistic instincts were ecstatic at this kill. The craving for blood inside him was fed from the sight. But, after glancing at his victim's face, it all changed.

Suddenly, he felt cold, deeply, sorrowfully cold. He slowly recognized the face, not just as prey, but as an identity. Cas. The angel's expression was one of pain and sorrow as the life was gradually fading out of him. Dean's expression faltered when he grew to realize his actions.

Oh, God, he thought. The blood no longer pleased him, but made his heart drop and his blood run cold. He watched the color drain out of Castiel's face in horror. Confusion and panic overtook him as he tried to sort through the events. How did this happen? How could he do this? One look at the Mark of Cain, who's glow had subsided, and he had his answer.

Now that the rage inside him had fell dormant, he was left with the repercussions of his actions.

"Cas," he spoke cautiously, almost as a question. The only response he got was the the angel slumping to the ground against the wall, holding his stomach.

Immediately, Dean was at his side, a hand on Cas' cheek, fear in his eyes. "CAS!"

He could see Castiel's nearly-dead eyes reopen and focus for a moment on his own. A deathly hollow look of happiness manifested in Cas's eyes. This was who he wanted to remember. This was his Dean.

"No... No, this can't happen..."

The angel tried to focus on speaking, but it was so difficult. Once death has its hand on you, it's nearly impossible to escape. His breathing was shallow and his words were scattered in his mind.

"...Dean... Thank you..."

The fear-struck man looked at the angel in confusion. "F-for what?"

"I have lived for... Millions of years," his breath kept catching in his throat, making the words difficult to for. "But, I never knew... How to be anything other than an angel... Until I met you. Thank you... Dean..."

Dean, who was listening intently, stuttered to form a response. "Y-you're welcome... Cas."

The dying angel put his remaining strength into forming a small, gracious smile, and his last few words.

"You made me free..."

He looked as though he wanted to say something else, but whatever it was died in his throat as his life force finally burnt out. His head fell to his shoulder and his eyes shut.

"Cas! No, no, no, no, you can't do this," Dean spoke as he shook Cas, attempting to revive him. His hand gripped the angel's cheek, trying to support his head. To Dean's despair, Castiel gave no response. His blood soaked his clothes and leaked onto the floor. Dean, who had his hand on the wound, frantically trying to stop the bleeding, also found it covered in the blood. He continued to speak Cas' name, as if trying to savor the moments that he could say it to the living owner of the name.

"No, please. I'm sorry, Cas. I didn't mean for this to happen. I need you, Cas..."

His eyes searched Cas' face for any signs of life, but there were none to relieve him. Castiel was truly gone...

He held the side of Cas' head and wrapped his other arm around him, bringing him into an embrace. One that, unfortunately, Castiel was unable to return.

Dean's whispering and muttering was almost inaudible. He just kept whispering "I'm sorry. I'm so sorry."

Finally, Dean couldn't take it anymore, and the tears started to come. He had had regrets. Oh, the list was endless. But, he had never regretted anything more in his life. Nothing.

"I need you here, Cas... I love you..."