<p>In the (unlikely?) situation that RAB isn’t Black or someone else with those initials, what if R A and B are three people? I still find it incredibly hard to believe that someone who was never very impressive (in Sirius’s, Voldemort’s and Slughorn’s opinion) was able to do what not even Dumbledore could do alone. That Horcrux’s defense was designed for more than one person, no?</p>