And Brass always did kinda have a fatherly way of looking out for Sara or busting her chops, as the case may have been.

I have to refer you to rant I made in this post a while back. It pretty much sums up what I think about that.

As for the Brass and Grissom friendship, you forget that the writers had Brass finding out that Grissom was leaving through the grapevine. I don't believe Brass has even acknowledged that Sara is back so the odds of them playing off each other are pretty much nil.