Harry spends the entire book struggling to complete a quest that his friend and mentor, Dumbledore, charged him with before he died. Harry consistently does his best to do what Dumbledore has asked of him, but the hardest thing about the quest is not its danger or mystery. Instead, it’s the doubts Harry feels about whether Dumbledore really loved him. When Harry learns that Dumbledore had a mother and sister buried in the same place as Harry’s parents, Harry wonders why Dumbledore didn’t tell him. When he can’t figure out what to do next, he wonders why Dumbledore didn’t give him the information he needs to complete the quest. Faced with the constant presence of Rita Skeeter’s malicious biography, he even starts to wonder whether Dumbledore was worthy of his love and respect at all. The struggle to keep faith with Dumbledore is every bit as important to the novel as the struggle to find and destroy the remaining Horcruxes.
Harry’s story demonstrates that the reason it’s so difficult to love the dead is that it’s hard to believe that they love you. They can no longer explain their actions or profess their love, and it’s easy to believe that they are simply gone, past caring about or loving anyone. This perception overpowers Harry on his visit to his parents’ graves. He is drawn to Godric’s Hollow because he longs to find some connection both to his parents and to Dumbledore, but all the trip brings him is the sense that they are gone and cannot hear him or answer back, ever.
And yet the book’s message regarding dead friends is extremely optimistic. The epigraph from William Penn declares that friends cannot be separated by death, though it takes Harry the entire book to find the truth of this. When Harry finally lets go of his fears that Dumbledore didn’t love him, he is rewarded with an inner Dumbledore—a Dumbledore in his own mind—who is so vivid and realistic that he is in a sense the real thing. Only then does Harry recapture his own love for Dumbledore.
Much earlier in the series, in Harry Potter and the Goblet of Fire, various characters speak of Dumbledore’s unusual, even extravagant belief in second chances. When people mention this about Dumbledore, they usually mean to imply that he is somehow gullible or imprudent. Harry and Ron refuse to believe that Snape might once have been a Death Eater but has since reformed—so Dumbledore’s belief in second chances is simply the explanation for how Dumbledore must have been fooled.
In this book, we see in a number of cases how wise Dumbledore really was. Most dramatically, we see how Snape turned his entire life around after he placed Lily Potter in danger, becoming Voldemort’s most trusted servant so that he could spy on him and protect Harry. Snape’s efforts proved indispensable to Harry and Dumbledore time and time again. Dumbledore remarks casually that “we sort too soon,” meaning that Snape might have been erroneously sorted into Slytherin house as a young man, and implying that his bravery might make him better suited to Gryffindor—if only the Sorting Hat could have taken into account how much Snape changed for the better.
We also see the reason why Dumbledore learns to give second chances, when we learn of his true early history. Faced with a sister irreparably damaged in an attack by Muggle boys, and with a father imprisoned for life for attacking those boys, Dumbledore briefly dreams of a world in which wizards rule Muggles for their own good. He quickly repents and spends a lifetime trying to repair his mistake, but he also retains a tolerance for others’ mistakes and a perception that love is a powerful motivator, capable of redeeming a person’s worst misdeeds.