Barnabas protected Quentin and Chris, because they were family (well, before he found out about Chris being family, he empathized with him). That's my theory.
I think in the older movies such as the Universal movies all the monsters got along. And come to think of it, in those movies, they never really interacted so much. After viewing Twilight purely on a whim, I can assure you that I will never watch another of those movies, BUT, I need to catch up with True Blood. I own the first season on DVD and want to get the second season. In that story line, the shape changer and the vampire actually vie for the affections of Sookie, if I'm not mistaken, so there might be the conflict there.
Perhaps these stories always reflect the current state of society? Who knows, I just watch for pure enjoyment.
one time a friend of mine was trying to tell me tha the Wizard of OZ of 39 was laden with poltical messages......