Author's Note: This is my first ever time writing fanfic and it may just be a one time thing. It doesn't have to be. If it works and you would want to read more, please say so!
"You aren't Dean." Even as the words left his mouth he wished he hadn't said them. Now the fear that was nagging at the back of his mind, the fear that was already asserting itself as a truth, would have to be spoken aloud.
The demon smiled, a black-eyed smile, Dean's smile but fundamentally wrong. "Come on Cas, really? After all this time, have you forgotten what I look like?"
"No." Castiel hung his head. It was true. Even now, human as he was, deprived of so many senses, he knew. It was true.
Dean stepped past the motel bed to where Castiel stood against the wall. He was so close now that his breath brushed warm against the former angel's cheek. "Did you miss me Cas?" That gruff voice, laced with honey and poison, slipped from the demon's lips- Dean's lips, which were now brushing Castiel's face. "'Cause I missed you. I waited for you Cas. I thought you were gonna come down and grip me tight, like you did before." he was breathing the words, soft and deadly, into Castiel's ear. "And, how did you put it- raise me from perdition?"
Castiel was pressed as close as he could get to the wall. He was shaking. Those black, bottomless eyes seemed to suck the life out of him. He wanted to tell Dean that he would have saved him if he could, that he had been only human. Helpless. That that feeling was worse than hell could possibly be. "I'm sorry," was all he could manage.
"Sorry?" Something like hurt, like betrayal had entered Dean's tone. Castiel felt his gut wrench. The voice was so familiar. "You left me in Hell Cas. You left me to burn. I thought-" He paused, smiling now, sadism etched in every line of his face, "I thought you loved me Cas."
At that, a cold shiver ran down his spine. How many times that thought had lingered in his mind, never finding words. How often he had watched the hunter, feeling something rise in his chest like words unspoken, only to shove it down again and tell himself that it was hopeless, that it was wrong.
"You know what's funny about that, Cas?" He leaned in to whisper in his ear, allowing his lips to trail along Castiel's jaw on the way. The points of contact tingled long after the touch was gone. "I loved you too."
Despite the imminent danger, Castiel's heart skipped a beat. His breath caught in his throat. Just as quickly the feeling died. It was the verb tense that killed him. Loved. Dean was gone; he could not love again.
"I never would have admitted it," Dean continued, "Or maybe I would've. Eventually. I told myself it was wrong, two dudes. I was too man for that." He was still whispering, dragging his lips back along Castiel's quivering jaw. "But now, now I just don't care."
That was when Dean did the unthinkable. He pressed his mouth softly against Castiel's. The former angel gasped as he felt Dean's tongue trace the outline of his lips. He felt a sudden surge of pleasure override his fear, nearly driving him to disappointment when Dean pulled away, trailing saliva.
"You like that Cas?" He laughed Dean's laugh. "It's a shame. This is all going to end with me killing you. But first we're gonna have some fun."
Castiel nearly jumped out of his skin when he felt Dean's fingers tracing the slope of his neck, finding his shirt collar, finding the knot of his tie.
"I'm going to make all your dreams, all your little secret fantasies come true. And then," Dean stepped back a little, black eyes twinkling with malice, holding Castiel against the wall by his knotted tie. With the other hand he reached down to his belt, tapped something fastened there. "I'm going to take this knife and stab you in the heart. I'm going to watch the light leave your eyes, Cas."
Castiel breathed heavily, his chest rising and falling against Dean's clenched hand. All the longing that had forced its way to the surface during the kiss had been suppressed again by terrible, paralyzing fear.