When everything becomes hopeless, only then do you really have a chance to think of the mistakes you made to lead up the moment you were trapped in.
A couple weeks ago he and Sam had attempted - and failed - to cure Abaddon, a knight of hell, of her demonic tendencies and turn her human again. All to complete some heavenly trials to seal the gates of hell up and stop demons flooding out of it like a broken tap.
But that's not important.

It had started as a completely normal day... Dean had found a possible hunt and decided to solve it, alone. Five bodies had been found in a farmers field on the outskirts of a small farming town in Iowa, throats slit and bloodied, faces which were barely recognisable. Authorities immediately assumed that they were ritualistic kills, probably from a cult that they made up out of thin air to account for the fact that they had no explanation or leads. That's when Dean had stepped in, posed as an FBI agent, prepared to go through any length to figure out what happened and kill the son of a bitch who did it. And within a couple days he had figured out it was a demon and he knew exactly where the demon was hiding.
Simple.

That's where it started going wrong...
Dean came to the door of the house where the demon was cowering. Assessing the situation quickly, he raised his foot and kicked the door off its hinges and it fell, splintered, to the floor. Satisfied with the result, Dean strode into the house with his gun in hand, loaded with three devils trap bullets. A handy trick he picked up from his grandfather.

Dean flowed through the house with expert precision, checking each room that entered his vision and slowly narrowed the hiding places down. The house clearly had been a base for months, blood splattered the once white walls and the floorboards creaked and cracked under the weight of the hunter. Silence was key.

Bang!
At the sudden show of movement from the end of the hall and Deans gun went off with a deafening crack, it left a perfect hole in the opposite wall but no dead body lay before it. Dean was on high alert, the demon was trying to get away. The only way it would be going would be down towards hell.

Trudging to the end of the hall, Dean cautiously poked his head around the corner, snapping it back just as fast whilst a vase went flying past and shattered on the wall behind him.
"Listen!" He shouted to the demon. "Come out and I wont kill you as painfully as I had planned." It was a long shot and obviously the demon didn't take up the offer.
Dean jumped out from behind the shield of the wall and fired another shot.
Bang!
But the demon moved, making a mad leap to evade the bullet.

"Come on!" Dean whined, already bored of the demons antics. "Let me kill you and we can both go home."
He saw a door swing slightly shut, the demon was cornered in a room, idiot. As the feeling of victory settled over him he sauntered over to the room, pushed open the door and fired.
Bang!
Only to hit a wall.
"What the fuck?" Was the only thing that escaped his lips when he came face to face with the scene in the room.

The demon lay crumpled on the floor, a small trail of blood streaked a line from the corner of his mouth and dripped silently onto the rotting wooden planks, staining them a deep crimson red. Over the demon stood a woman. A leather jacked was strewn over her shoulders and a 'Devil Made Me Do It' shirt was shining with fresh blood, unmistakable red hair framed her pale face.
Abaddon.

"Hello there." She spoke with a forced smile but her words carried hatred. "How have you been, Dean? Hunting, I assume."
Dean pointed his gun, aimed straight into the middle of her head and pulled the trigger.
Click.
And again.
Click.
She gave a light tutting sound and walked forwards, seizing the gun from Dean's grip and threw it blindly behind her. "Should have packed extra." She whispered, making the hair on Dean's neck stand on ends and a chill ripple through his body. Dean turned to her, his face etched with disgust, "Bite me."
Abaddon smiled lightly, "Oh, sweety, I intend to."

Her hand shot forwards, gripping Dean around his neck and cutting off his airway. She pinned him to the wall and didn't relent until Dean was going a sickly purple color.
Her free hand slowly traced his chest, a feeling of cold followed suit. "Well, aren't you just the specimen." She said, admiring the way his shirt clung to his chest. Her hand came to a stop over the left side of his collar bone and what followed was an immense heat and agonising pain.

Dean looked down as he watched the area under Abaddon's hand burn and bleed, taking away the skin and leaving it raw and open.
And with the skin, the anti-possession tattoo he had for years.
He looked at Abaddon and steeled his expression. He knew what would follow and he wouldn't go lightly.

He threw his head forwards, his connecting perfectly with her own and a nauseating crack was heard, Dean's vision blurred as he fell to the ground, the grip around his neck disappearing as Abaddon pulled away, shocked at Deans stupid attempt at getting away.

But she was sure that it would not happen. Abaddon opened he mouth and the putrid black smoke fell from it, collecting on the floorboards beside Dean. His vision was still swimming, lack of oxygen and a knock to the head wasn't helping his situation as he tried in vein to get the feeling back into his fingers.
It just wasn't happening fast enough.

The smoke edged its way along the floor, as if taunting the immobile hunter, before flowing unhindered into Dean mouth, forcing its way into his mind, pushing Deans consciousness into the depths of his own head.

Next he stood easily, brushing off the little bits of dust and wood chip on his shirt and jacket. You would be fooled, though. The only remnant of Dean was the physical appearance, except his eyes. Eyes which were full of hatred, dull and black.