Here we find further clarity regarding the Wreckage Brother. Not only is Juan Avus brother to Cornelius Avus, whose body will be found in the wreckage of the plane, but the man who leaves the plane alive will be brother to the body injected with his blood—quite literally, they will be related by blood. Furthermore, stating that they will find Juan Avus in the Wreckage Brother does not simply mean that the body will be mistaken for Juan, but that the discovery will be true. It really will be Juan’s essence in that body, and the man once called Juan Avus will be no more.
With the death of Cornelius, he will lose his only living link to his past, becoming reborn as a tool to be used by Bane, as shown in deleted scenes where Bane forces him to build a nuclear device. This is the only remaining purpose of the man who can now only be known as Doctor Pavel Heere, his past now in wreckage with no survivors.
It is here, after understanding this hidden relationship, this shared hidden past destroyed by the Master Plan, that Christopher Nolan’s true genius reveals itself. This is where the tragic subtext takes on transcendent, spiritual significance, and we comprehend what it is for an identity to die while the body survives. Through Bain’s actions, through his will, he forcibly maintains the identity of Doctor Pavel Heere—and, I would argue, creates it anew by making him into a mere tool. He also creates the Wreckage Brother who will stay behind.
Hold on a moment—if the body is the Wreckage Brother, then what is the true name of the plane? Is it something we simply cannot know?