In Metallicar on the way to the Montgomery's, Dean tells Sam he's good with having a chat with their suspected Rugaru. "I just want to know if push comes, you're gonna shove." Sam is now over-identifying with Jack so strongly that he can't keep focused on the fact that Dean's willing to talk -- that he just wants to know what to do if talking doesn't work. He gets on Dean about calling Jack 'this guy', reminds him he has a wife, and blah blah blah. He's so obvious, even Dean sees it, and accuses him of letting his emotions get in the way. When Sam comes over all obtuse, Dean spells it out for him. "You know, nice dude -- but he's got something evil inside of him. Something in his blood. Maybe you can relate?" Meeee-ow.