Harry Potter and the Prisoner of Azkaban, there's a definite interplay between setting the stage for future and coming to terms with past. You have to deal with the past and get it out of the way before moving on. And we have two types of pasts that people deal with here: personal memories (such as Harry's haunted, Dementor-triggered flashbacks) and collective, community memories (such as everyone's "recollection" of what crazy Sirius Black did to get a one-way ticket to Azkaban). Perhaps this is the reason for the absence of Voldemort in Book 3. If the Chamber of Secrets was about Voldemort as young Tom Riddle, then Azkaban is more about the characters' personal and collective memories of Voldemort during the height of his power.
The past also conveniently acts as an umbrella theme in the novel, meaning that it sort of encompasses all the other themes. More specifically, it's tied to themes of fear (see the lingering fears of all things Voldemort-related), themes of secrets (the past is a mystery that reveals itself to Harry), and themes of growing up (since part of growing older involves learning about and dealing with the past). The past is everywhere you turn in Book 3, so learning about the past and dealing with memories becomes a right of passage here that ultimately connects Harry to the wider wizarding world.
FDR would have a field day with this book. As you probably know, FDR (a.k.a. famous American President Franklin Delano Roosevelt) was famous saying "there is nothing to fear but fear itself." Lupin gets his FDR on in this novel when he tells Harry that it's "wise" (8.4.53) to be most afraid of fear itself. Aside from letting us know that FDR would totally be a Harry Potter fan, that scene also highlights the lack of Voldemort in the novel. (Sure, we keep bringing up Voldemort's absence, but his MIA status is a hugely important thematic detail. See, this novel is more about internal battles and character development than external fights; having lots of big external conflicts would detract some from that.)
Still, in Book 3, it's the Dementors that really highlight the theme of fear. These creepy, reaper-like characters embody fear, death, and darkness. The Dementors are giant walking (or gliding) metaphors for the world that Voldemort represents. Luckily, we also get the flip side of fear, as represented by the Patronus charm. Light is literally used to battle darkness here. It's worth noting that being around Dementors reminds people of horrors from their past and makes them forget who they are. The past itself can haunt and create fear. And forgetting happy memories can erase a person's identity, which implies that people aren't defined solely by their fears or their inner darkness. So while details like a character's boggart give us important insight into that character, the novel also cautions us against identifying people just by their fears.
The Harry Potter series is a classic tale of good vs. evil, ranking up there with things like Star Wars, Lord of the Rings, and The Chronicles of Narnia. But Harry Potter and the Prisoner of Azkaban really starts to complicate ideas of good and evil – they're certainly not black and white. Nope, this book is about the transition to adulthood, and we all know that journey is full of moral ambiguities, confusion, and difficult choices. The details we learn about the Marauders (James, Sirius, Lupin, and Peter) epitomizes this – their actions as Animagi were dangerous and even morally questionable. We have lots of other good vs. evil complications too: Sirius doesn't always act like "an innocent man" (21.76), Pettigrew is a despicable coward but also pitiable, Snape is presented as both a victim and a villain, and even Ron and Hermione's fights boil down to neither being fully right nor fully wrong.
However, the spells that Harry learns throughout the year put him firmly on the side of good and make certain distinctions clear. Harry uses laughter to fight fear, light to fight darkness, and happiness to fight despair. And we're guessing that these are a big hint that Harry will really need those good tools as he moves into a more uncertain, darker future.
The movie version of Harry Potter and the Prisoner of Azkaban really emphasizes time and clocks, which is quite fitting because Book 3 will probably always be remembered as the Harry Potter book with the time travel. Though it's downright tame compared to Lost (Hermione turns an hourglass, not a donkey wheel), this time tinkering is still pretty trippy. Harry and Hermione live out a time loop where everything somehow fits together in the end like a jigsaw puzzle.
But time and its progression is far from neat and tidy and predetermined here. Time can seem impossibly, cruelly slow – see Harry waiting for his Firebolt or Sirius's interminable twelve (unnecessary) years in Azkaban. Time can be also insanely fast – see Hermione's jam-packed schedule or the meager time allotted to save Sirius. And time can be taken away as well – see Harry's lost time with his parents or Sirius's lost adulthood.
It's fitting that the Time-Turner doesn't fix everything in the end; though Harry and Hermione use it to free Sirius and Buckbeak, they can't use it to clear Sirius's name. As the kids learn, time is what you make of it, and having more or less can be both a good and bad thing. So it comes as little surprise that Hermione returns her Time-Turner at the end of the year.
Harry Potter and the Prisoner of Azkaban is a partial mystery novel with a series of secrets and inadvertent lies, which may be the most dangerous kind. It seems like nearly everyone has a secret in this book: Harry tries to keep his reaction to the Dementors under wraps; Hermione doesn't tell even her BFFs about her Time-Turner; and all the adults try to keep the "truth" about Sirius Black a secret from Harry. It's notable that the secret of Sirius Black is actually a lie; the real secret there is only known by Peter and Sirius for much of the novel. Secrets and lies, both intentional and accidental, start overlapping in this novel and raise a lot of complicated questions: is it ever OK to lie to your friends? Do secrets protect people, or can they do more harm than good? The themes of secrets and lies are summed up nicely with the idea of the Secret Keeper, which played a crucial role in the fate of Harry's parents.
The Prisoner of Azkaban pays attention to the psychological effects of imprisonment and confinement on its characters. In Book 3, aside from the obvious prisoner in the title, Sirius Black, we also see the effects of different kinds of prisons on characters like Harry (a prisoner at the Dursleys' house), Hermione (trapped by her own overachiever tendencies), Peter (stuck living life as a rat out of cowardice and fear), and our new pal Lupin (trapped by his condition as a werewolf). But despite all these themes and images of prison, we do get some freedom in the book too. Freedom is most strongly represented by flight, be it on brooms or on Buckbeak the hippogriff.
The Harry Potter series really boils down to the power of friendship more than any other thing. But friendship isn't glossed over or presented with rose-colored glasses here. We see fights, personality conflicts, disagreements, and the difficulty of maintaining close friendships with people. But even with these difficulties, Harry, Ron, and Hermione always come back together after they are separated. Plus, we get some extra bang for our buck with this theme in Prisoner of Azkaban since it introduces us to an older generation of buds – the Marauders (James Potter, Sirius, Lupin, and Peter). Through tales of the Marauders and glimpses into their past, we get a chance to see how close friendships operate in the adult world and in a time of war. While our favorite trio is at the heart of novel, the other friendships we see, whether it's Lupin and Sirius or Hermione and Hagrid, play a very important role here too.
If Harry Potter is searching for one thing in his life, it's probably family. And in a lot of ways he's found family – through his friends, through the Weasleys, and now through his father's old buds. Family is about much more than just blood ties here – it's about qualities like loyalty and love. Sirius sums up this theme best when he's interrogating Peter Pettigrew: family are people that you sacrifice and even die for, with the knowledge that they would do the same for you. With this, family ultimately boils down to trust. For example, trust supersedes things like the sibling rivalries and funny interactions we see between the Weasleys, who are probably the best representative of the theme of family in the Prisoner of Azkaban. And finally, above all else, family is about choice. Characters here choose to be or not to be families regardless of whether actual blood ties exist.
Justice isn't something that's set in stone in Harry Potter and the Prisoner of Azkaban. It isn't the hardcore justice we see in Justified, the final "dun-dun" judgments we get in Law and Order, or even the vigilante justice of something like Batman in The Dark Knight. In fact, in the Harry Potter series, justice and punishment are issues that are up for debate. The scene that best demonstrates this is when Harry asks his father's friends to spare Peter. There are competing ideas of justice swirling around here – we have justice as vengeance, justice as mercy, justice as punishment, and justice as forgiveness (phew!).
We can trace this theme backwards throughout the entire novel too – Sirius's imprisonment and punishment, Buckbeak's trial, Ron's grudge-match punishment of Hermione. Justice is hard to mete out but it's a responsibility that Harry and other characters have to struggle with throughout Book 3. As Gandalf tells Frodo in The Lord of the Rings, you shouldn't be too eager to cast judgment or dole out punishment for others. This is a lesson that a furious Harry, longing for revenge for the huge injustice of his parent's murder, has to learn over the course of the novel.
Harry Potter and the Prisoner of Azkaban isn't so much about forgiveness as it is about the difficulty of actually forgiving someone. Forgiveness and compassion are ongoing processes here, and they are things that don't come naturally to every character. Throughout the novel we're confronted with situations that may or may not be forgivable. Ron manages to forgive Hermione for her role in Scabbers's "death," but Snape doesn't get over the almost-deadly prank that James, Lupin, and Sirius played on him as schoolboys. Some things seem unforgivable, such as Peter's role in the death of Lily and James. But, as Harry's actions toward Peter demonstrate, even unforgivable acts can inspire mercy.
The Harry Potter novels sort of act as their very own The More You Know PSA – the things that Harry and his fellow students learn during the school year always turn out to be very important to the novel as a whole and to the adventures Harry inevitably gets involved with outside of school. Education does pay off, after all! Hermione's knowledge saves the day frequently, and the spells Harry and his friends get from class always have thematic significance. This year the theme seems to be happiness and light – things to fight darkness and fear. Harry Potter and the Prisoner of Azkaban is a novel of preparation for darker fights to come in lots of ways, and the preparation and education occurs outside the classroom too. Learning how to be an adult and to start surviving and doing good in the wider world is an important part of Book 3.