When Sam asks Dean to go through with the promise he made to their father - to kill Sam if he can’t prevent him from going bad - Dean finds himself unable to go through with it. This may be the only order their father has ever given Dean that he can’t follow through with. But of course he couldn’t do it. Of course Dean could never, ever hurt - or hope to kill - his baby brother (x).
President JF. Kennedy & Marilyn Monroe