I personally dont think that Regulus Black is RAB cuz its to easy to figure out

JK Rowling usually doesnt just pick the easiest solution to something that keeps us hanging

I mean we wouldnt be waiting faithfully counting down the days until book release time if it was going to be predictable right??

Anyways, JKR wouldnt make it Regulus Black cuz its to easy----- now b4 ppl who do think it is Regulus hold on i am not done

It might be possible that Regulus was an acomplice bcuz member when Harry and Dumbledore are in the cave and Dumbledore says that it was a good plan bcuz u couldnt do it alone--- I think someone else that is either on the backburner or is somebody that nobody would expect went with Regulus or helped him

Give sum ideas on what u think of my theory or who u think RAB is