The demon smiled widely as he watched the angel fell into the hunters arms.
He did it; he finally killed the great Castiel. Score one for Hell.
Then he saw the green eyes that belonged to the hunter and his blood froze.
He knew of the relationship between the angel and the hunter; anyone with half a brain could see it.
As he looks at the human with his arms now burned with the wings of the angel, he knew he made a fatal mistake.
He remembers his boss Crowley saying that the Winchesters were denim-clad nightmares that everyone underestimated.
As he stared at the slowly rising Winchester stood up and charged at him with an angel blade, he knew.
Dean Winchester was going to bring hell on earth.