Finally, we see that Dumbledore is wise enough to see the flaws in Ron’s character and foresee the mistake Ron will make, giving up on Harry when things get too tough and there’s no one to lead Ron or provide for him. So Dumbledore arranges for Ron’s second chance ahead of time, bequeathing him the Deluminator that will lead Ron back to Harry and Hermione when he’s ready to rise to the occasion.
The only person capable of planning and orchestrating Voldemort’s downfall is Dumbledore, because no one but he has the wisdom or knowledge to piece together what Voldemort has done and figure out how to undo it. And yet Dumbledore knows that this difficult work will only be completed after his death. Not only Harry, Ron, and Hermione, but also Snape, Lupin, Moody, and all the members of the Order of the Phoenix have to keep doing their part after Dumbledore’s death, carrying out his vision. As we have seen, believing in Dumbledore’s quest after he is dead is not easy for Harry, nor is it for any of the others.
But Dumbledore is not the only dead character who needs the loyalty and love of the living. Snape is a loyal follower of Dumbledore, but his loyalty and bravery are really a manifestation of his need to stay loyal to Lily Potter, keeping faith with the woman he loved after her death. Dobby the house-elf gets himself killed saving Harry and his friends from Malfoy Manor, and the process of burying Dobby helps put Harry into a better frame of mind about his mission. There is no mystery about Dobby or his death: Bellatrix kills Dobby for helping Harry, and Dobby dies in Harry’s arms, and all Harry can do is honor the house-elf’s memory and try not to let that memory down. This experience snaps Harry out of his ambivalence toward Dumbledore, reminding him that he made a promise to his dead friend that he needs to honor.