Demon!Dean
Well let's say Dean forgets his humanity and indeed does become a demon like he was predicted to be. This whole plan was using Sam's weakness was set in stone and meant to happen. I've had this idea of when Dean became a demon, he becomes the lover of the demon who takes charge of the Army Sam was meant to lead. Now in my mind Dean is the demon of all demons, and the most beautiful among all of them. I'm not sure what kind of demon he would be though.
It's about 3 or 4 years after Dean is dead and Sam is still hunting, fighting the War that isn't close to ending. Of course demon!Dean makes an appearance to Sam.
I have tons of ideas for this but I just want to know if anyone would please write it? I am willing to make you a vid if you do!