Dean/Sam
He knew that there was something wrong with me, Dean. He had to have known. Why else would he have been so quick to tell you that you MIGHT have to kill me? Do you think that he could have come to that conclusion within a few short months? No. He knew something. And if that wasn't obvious enough, then the fact that he said that MOM knows something about it all and was so desperate to keep me from interrogating her about it does. Open your eyes. I know you're not that blind.
I respect, Dad, Dean. I do. But if he's going to be an asshole, then so am I.