What Jared said their interactions were going to be was directly contradicted by what their interactions were on screen. I do agree that Cas tends to see people in relation to Dean, though I think his and Sam's relationship has taken on a life of its own in s6 and s7, but he certainly showed no sign in 7.17 of resenting Sam for the apocalypse, and Sam was not wary as Jared suggested, but eager to help and communicate in 7.21.