personally I dont think Regulus Black would be RAB. Since he wasnt a great wizard and from the locket, it seemed like it was switched. So for someone like Dumbledore and Regulus to take such difficulty to figure out how to pass all the restrictions and for Dumbledore to suffer from so much pain, I would think it would take a much more powerful and intellegent wizard than Regulus to obtain the locket. Plus, RAB could very well just be standing for a nickname rather than initials which would be far too obvious.
I did really enjoy reading about DD's lessons with harry. I think the fact that in all those lessons he was teaching him about Voldy's past rather than defence skills is showing Harry that knowledge of Voldy and how to use these clues to find the hocruxes was more important as Snape as pointed out -harry isnt a very good attacker. I would think it would be rather unrealistic for harry to suddenly be all powerful for even DD said that it wasnt that harry was in himself special. IT was the fact that Voldy chose harry and the fact that lily saved harry that made him special?
AS for Snape, I dont think his evil and thus i do not think dumbledore is a fool. It didnt seem like DD was pleading for his life, merely for Snape to do what he had to do. All the lessons was to pass to harry everything he knew about voldy in case harry had to carry on without him, in case snape had to finish draco's job. Perhaps draco would play an important role in the last book? Its good to see different aspects of draco's personality. How he is in front of his friends, his enermies and by himself. Perhaps Snape or his mother was the one who was RAB and the ones who concocted the potion that secured the bracelet since they were such potions masters. And perhaps that was why DD asked for snape when they arrived at hogsmede.
A theory that I have is perhaps Snape liked lily? I really doubt that he is dracos father though as he was rather reluctant to save draco and did the vow more for his mother. Plus draco looks way too much like his father. I think the fact that Snape felt really bad for the death of lily was why he left the death eaters. And then to have harry potter, who although is lily's son, also looks just like james who took lily away from him. So even though he despised harry since he reminded him of james, he didnt try to kill him. Was it just me, or did anyone else feel like when he was blocking all harry's shots he was kind of like teaching harry? like ...oh this curse is no good...try another? Also the fact that voldy allow lily to live if she ran away, for a person who was all evil and merciless and doesnt think twice about killing whole families? Perhaps he himself had made an unbreakable vow with severus when he revealed the prophecy and that he broke it by killing lilly and thus resulted in him in his non-physical form since he could not die due to the horcruxes.
