I just had a kind of a thought.
So. When Harry walks to what he believes is his death, he is protected in two ways. The first is through the link that Voldemort made with Harry's blood. As Dumbledore explains, he tethered Harry to life while he lives. The other way lies in the Elder Wand. At the time Voldemort casts the Killing Curse at Harry, he wields the Elder Wand. But Harry is the true master of it, due to having disarmed Draco at Malfoy Manor.
So. When Voldemort casts his AK, he unknowingly destroys part of his own soul. Harry and that mangled bit of soul are transported (metaphysically, since it happens inside Harry's head but is still real) to an existence between existences, almost like Lewis's World Between the Worlds. There, Harry is able to converse with Dumbledore, getting answers for what has occurred and gaining strength for what must follow.
Now. Dumbledore tells Harry that since Voldemort used his blood, he can return to life, and finish Voldemort once and for all. But he also says that there is a possibility that Harry can move on. Why is that? If Harry's blood protected him from Voldemort's curse, then it should simply have rebounded, or failed. Instead, Harry is given a choice: go back, or go on. I think the second part of the choice is due to the Elder Wand.
Because Harry is the Wand's true master. What he wills concerning it, at least in regards to how it works upon himself, is what will happen. Maybe the very fact that he was able to talk to Dumbledore in Kings' Cross is a reflection of his power over the wand-- he wanted answers, and the wand was able to bring Dumbledore to supply them. But I digress. Because Harry is the master of the Wand, he can choose what happens. He can either will the curse to affect only Voldemort's soul and not him, and return to Hogwarts, or he can choose to let the wand kill him-- by which act Voldemort would, I suspect, become the true master of the Wand. What this means to the tethering of blood, I'm not sure. Perhaps Harry could have chosen to have the wand break that bit of magic as well. In any case, he chooses to go back. The part of Voldemort's soul that had ridden him for nearly 16 years was left behind.
This ability of Harry's to control what the wand actually does in regards to himself also explains the strange effect the Cruciatus Curse has upon him. Harry desperately needed to convince Voldemort that he was dead, but the pain of the Curse would make that almost impossible. So the wand did what Harry wanted-- his body was tossed around as though the curse had worked, but Harry felt no pain. And when Voldemort once again tried to kill Harry, Harry's Expelliarmus not only disarmed Voldemort of the stolen wand, but also allowed Harry to direct the Avada Kedavra back on its creator.
The rest of Hogwarts being protected from Voldemort's spells is still explained by Harry's willingness to die for them, although I suppose some of it may be explained by Harry not wanting anyone else to get hurt.
I think it makes sense. What about you?
Dumbledore essay is still coming.