Castiel was anxious to get back to the bunker. The adrenaline that originally drove him was dissipating now that Metatron was captured. Metatron had told him that Dean Winchester had died but Castiel didn't know if he was lying or not: He had a tendency to tell stories.
He would try to call, but Sam never answered his phone, and with every unanswered ring, Castiel's heart sunk. The drive back to the bunker had taken a couple of days, and every night, when Castiel laid on the stained beds inside cheap, shoddy motel rooms, his anxiousness would fester and feed off his insecurities and grow and wrap around his mind like a morbid vine. His thoughts would be plagued by the unpleasant fruits from the vine even after sleep took hold of him.
When he finally arrived at the bunker, he opened the door to the gold Lincoln Continental and breathed in deeply, gathering the courage to go in. He thought of every bad thing that could've happened. He thought of Dean's possible death, and how it could've happened, and what happened to Sam? The cold handle of the bunkers steel door brought him out of his dark reverie. He slowly opened the heavy door, it's creak echoed throughout the bunker. The familiar stagnant air pushed through Castiel's nose and greeted him with joy. Castiel's hands ran down the unlit stair rail gathering a thin layer of dust in his hand.
"Hello?" He scanned the bunker halls, finding only unlit doors and empty rooms. He smelled the vague stench of sulfur which spiked as he passed Dean's room. He hesitated and thoughts of murder clouded his mind once again. He opened the door, not really knowing what to expect. Sitting on the bed was Dean; His broad shoulders hunched down, his arms rested on his legs. "Dean?" Dean turned and stood up. He was covered in blood, as was the First Blade which he held in his hand.
Dean smiled and laughed slightly. "You should really see your face," he said, waving the First Blade haphazardly.
"Dean," Castiel couldn't look him in the eyes. "no…"
"You like the change?"
"You died? The Mark did this to you?"
"Yup, now look at me." Castiel couldn't. His gaze stayed locked on the floor.
Castiel swallowed. "Where's Sam?"
"Who knows? I haven't seen him since I died."
Castiel pointed to the blood on Dean's shirt. "Then whose blood are you covered in?"
"Well," Dean looked down at his shirt then back as Castiel. "Crowley decided to pay me a visit. He told me all about the Mark's power over me, how it wouldn't let me go, and how my new life was just beginning, blah blah blah." Dean looked at Castiel, whose eyes returned to the concrete. "Anyway, as he was talking, a thought suddenly popped into my head: I could kill him, and reign over Hell. So," He twirled the tip of the blade on his finger. "I killed him. Simple and clean. Well," He stepped back and spread his arms out wide. "not so clean."
"Dean," Castiel looked up.
"Would you stop saying my name? I know who I am, thank you very much."
"No, you're not him. Dean would never gladly reign over Hell."
"Oh, I would. But not without a partner."
"Where's Sam?!"
"Luci," Castiel turned to see Sam standing behind him, but it was not Sam.
"No."
Castiel could see their true faces. Dean's lit up, his once green eyes turned black, yellowed horns curled from Dean's temples, and skeletal wings hung from his shoulder blades. Dean's spiked, blood stained teeth were uncovered in a grisly smile. "Oh, yes."