There's been a rash of massacres across the nation since Lucifer became free to walk across the Earth. Or more rather, the world, but the murders that jump out at Dean through headlines in newspapers come from across the States. The first massacre he reads about he ignores the familiarity between what is described and what he knows they are leaving out.
The second massacre happens, even bigger than the first. More blood, less body parts found, more creativity in how the bodies are arranged.
The report doesn't bother to even describe the scene, but Dean knows the details. He knows how the blood pooled, how some of the bodies will have charred marks on certain parts of the body, which limbs were fed to which victim. He doesn't tell Sam about it.
The third massacre is devastation. A middle American town's population dropped to zero. This time Dean doesn't have hear the reports, he dreamed all of it. He felt the childish joy soak through him at each kill. He saw every plea for mercy, and he saw every inch of mercy eviscerated.
The third massacre brings Dean and Sam to the small town to find a circle of fire containing a disemboweled Castiel.
A Present is written in blood across the basement floor of a once happy home.
Dean barely keeps himself together long enough to douse the flames which imprison the Angel. The last flicker of light quells and Castiel is no longer covering the floor. He is as he is supposed to be. Dean doesn't look him in the eye, but he does.
"This was unexpected."
"What did this?" Asks Sam.
"A very creative demon," Castiel responds to Sam while still looking at Dean, "What did you dream of last night, Dean?"
Dean finally looks him in the eye.
"We need to stop him." He finally Says.
"You know him, Dean?" Asks Sam
Oh, we've more than met, whispers across his mind and he just knows Castiel can hear it too. Say hello to Cas for me. He was a great playmate.
I'll find you.
I'm counting on it.
After that they start finding other Angels trapped and their vessels tortured. At first it's only across America, but slowly the body count rises across the world.
He likes to pin their wings down like a collector of butterflies. Watch as they struggle against his hold.
His count is one hundred and twenty two Angels trapped, and if he thinks about it, that makes it double the victims. He got to torture the meat off the bones of humans, and trap the Angels so they could do nothing against it.
This, he concludes is so much more fulfilling than working on a rack.
And he's got this chase going, leaving behind a few bloody bread crumbs for his other to follow.
He wonders how long it will take his other to join him. He will. He knows himself too well.