Originally Posted by sediment
Yes, but if The RAB is actually Black's brother as suspected, perhaps he changed his ideas about purebloods and such. Of course he didn't actually destroy the locket (if they found it, then it must not have been destoryed) so maybe he kept it around just to have a bit of power over Voldemort. I think many here are suspecting that Regulus may have turned away from the Death Eaters and therefore his pureblood biases. Still, I agree with you that he probably won't take Sirius' place in Harry's life because I just hate the idea of ANYONE (except perhaps Lupin) doing that.
And, Dumbledore has to be back in book seven because his picture is in McGonagall's office, so he can offer advice. I never really understood how much pictures can really do, so maybe he can even tell more of what he knows, like whether Snape is good.