The Deanmon scares me. He really does. One of the few things that the Fandom had to lay our weary heads to rest upon was that Dean and Sammy would be OK. No matter what happened, they would be together and they would help each other. Their brotherly love would stand the test of time.
One of the defining things about Dean is that he takes care of Sam. That was and is his job. That's the responsibility that was thrust upon him the second he carried baby Sammy out of the flames. And a responsibility that was reaffirmed when he carried him out of the flaming dorm room away from Jess.
Now Dean isn't taking care of Sammy.
He's not the Dean we know and love.
He likes the disease.
I've seen a lot of people freaking over the Crowley/Dean-Bitch/Jerk thing. I think the writers did that to show that this is Dean. This is the bowlegged, green-eyed, plaid-clad hunter we've always loved. But even though it's Dean, it's a perversion of him.
His knee jerk reactions might be the same, but Bitch/Jerk-ing has lost the innocence that it had with Sam.
I think that's how the Demon!Dean is gonna be. He'll be the same, but less innocent, for lack of a better word. We've seen the bad things Dean has done whilst trying to save the world: what will it be like if he's actively trying to hurt it?
It scares me.
I do not like the disease.