[The black dog appears in the park.]
When Harry flees from the Dursleys, he thinks that things can't get much worse. But being alone, in the dark, and encountering a snarling dog is pretty freaky. Not enough to make a room in Uncle Vernon's house look appealing, but still scary, and quite a way to start the movie.
STAN SHUNPIKE: That is Sirius Black, that is. Don't tell me you've never been hearing of Sirius Black. He's a murderer. Got himself locked up in Azkaban for it.
The threat of Sirius Black hangs over Harry even before he gets to Azkaban. Even before we learn that Sirius might be targeting Harry, we're still nervous that a deranged maniac is on the loose.
RON: I felt weird, though. Like I'd never be cheerful again.
The Dementors are the essence of fear itself. What could be scarier than never being happy again?
HARRY: But someone was screaming. A woman.
For Harry, the Dementors are even more terrifying, because he hears the screaming of a woman whom he believes to be his dead mother. Yikes. That's the stuff of nightmares.
DUMBLEDORE: Dementors are vicious creatures. They'll not distinguish between the one they hunt and the one who gets in their way. Therefore, I must warn each and every one of you to give them no reason to harm you. It is not in the nature of a Dementor to be forgiving.
The Dementors make Hogwarts into a terrifying place, instead of a safe haven. (We still think that a Dementor-infested Hogwarts is less horrific than, say, an abandoned amusement park.)
DUMBLEDORE: But you know, happiness can be found even in the darkest of times if one only remembers to turn on the light.
Our resident Yoda is basically saying that, even when you're scared, you need to look for something positive to get yourself through the darkness. Easy for one of the most powerful wizards on the planet to say!
LUPIN: What really finishes a boggart is laughter. You need to force it to assume a shape you find truly amusing.
Lupin teaches the students the "Riddikulus" charm to combat boggarts. It's a wise lesson, one that can even be followed in real life. Simply laugh in the face of fear, and suddenly you're not scared anymore.
LUPIN: That suggests what you fear the most is fear itself. This is very wise.
Lupin should leave the words of wisdom to Dumbledore instead of cribbing this bon mot from FDR.
RON: It's meant to be the most haunted building in Britain.
In a book filled with fear, there's plenty of foreshadowing that the book's climax will occur in the "most haunted building in Britain," the Shrieking Shack.
LUPIN: Dementors affect you most because there are true horrors in your past. Horrors your classmates can scarcely imagine. You have nothing to be ashamed of.
Poor Harry. The Dementors take advantage of his past trauma when they prey on him. And this history of trauma is a part of Harry's character that will return later in the books.
HAGRID: How am I doing me first day?
Hagrid knows that Harry, Ron, and Hermione are loyal to him, so he turns to them for emotional support on his first day as a teacher. He needs them because Draco and his pals will try to sabotage him.
MCGONAGALL: Years ago, when Harry Potter's parents realized they were marked for death... remember? They went into hiding. Few knew where they were. One who did was Sirius Black. And he told You-Know-Who.
Friends are important to Harry Potter. It shows us how strong his friendship to Ron and Hermione is, because he never considers that they might betray him the same way.
HERMIONE: If you want to kill Harry, you have to kill us too!
Hermione's definitely loyal to Harry. She'd do anything for him. This sets her and Ron apart from the sniveling Peter Pettigrew.
SIRIUS: I would have died! I would have died rather than betray my friends!
Sirius lets his true nature show here, and he continues to prove it throughout the series. He'll risk himself to save Harry more than once.
HARRY: Well I just didn't think my dad would have wanted his best friends to become killers. Besides, dead, the truth dies with him. Alive, you're free.
Harry repays Sirius's loyalty by giving him peace of mind. And it proves to Sirius that Harry believes him, and will now be loyal to him too.
SIRIUS: I don't know if you know, Harry but when you were born, James and Lily made me your godfather. […] I can understand if you choose to stay with your aunt and uncle but if you ever wanted a different home...
Sirius attempts to earn Harry's trust and loyalty by offering to be a father figure of sorts to Harry. However, the movie doesn't really address the fact that Sirius takes back this promise at the end. Does Harry feel betrayed when Sirius tells him no, he can't actually live with him yet?
FRED AND GEORGE: It's a Firebolt. It's the fastest broom in the world.
However, Sirius does show Harry that he cares about him by…replacing his broomstick. Events outside his control prevent Sirius from staying with Harry for the moment, but he will do for Harry whatever he can.
MARGE: You mustn't blame yourself about how this one turned out. It's all to do with blood. Bad blood will out.
Although Marge's comment doesn't apply to Harry as intended, perhaps she's onto something. All the Dursleys seem to be terrible people, so maybe they're the ones infected by bad blood.
MARGE: It's all to do with the mother. You see it all the time with dogs. If something's wrong with the bitch, then something's wrong with the pup.
Marge goes a bit too far calling Harry's dead mother the b-word. Insensitivity is something else that runs in the Dursley family.
LUPIN: I knew her. Your mother was there for me at a time when no one else was. Not only was she a singularly gifted witch, she was also an uncommonly kind woman. She had a way of seeing the beauty in others even, and most especially, when that person could not see it in themselves. And your father, James, on the other hand... he...he had a certain, shall we say, talent for trouble. A talent, rumor has it, he passed on to you. You're more like them than you know, Harry. In time, you'll come to see just how much.
Lupin's Lily lovefest proves what we already know: that Harry's mother wasn't at all like Marge described her. Even though we knew that, it's nice to be reminded.
MCGONAGALL: Sirius Black was, and remains to this day, Harry Potter's godfather!
Harry's family tree gets complicated when he discovers that Sirius Black is his godfather. Of course they're not related by blood, but Sirius is the closest thing to a parent that he has. It's alarming for him to discover that he might be even worse than the Dursleys.
HARRY: I was thinking of him. And Mum. Seeing their faces. They were talking to me. Just talking. That's the memory I chose. I don't even know if it's real. But it's the best I have.
Harry must think of a happy memory to conjure a Patronus, so of course he thinks of his family. These tiny memories of his parents keep Harry going in dark times, and the more he thinks of them, the more real they seem to him. He'll never forget them.
SNAPE: How extraordinarily like your father you are, Potter. He, too, was exceedingly arrogant, strutting about the castle.
Lupin already said that Harry is very similar to his father. That's why Snape dislikes Harry, because of that similarity. Snape was always jealous of James, and Harry reminds him of his own insecurity.
LUPIN: Your father never set much store by the rules either. But he and your mother gave their lives to save yours. Gambling their sacrifice by wandering the castle unprotected with a killer on the loose seems to be a pretty poor way to repay them!
Sirius may be Harry's official godfather, but Lupin fills that role when Sirius is unable to—whether it's because he's a fugitive or currently a dog. He reminds Harry that, even though his parents are dead, he should still try to live as they would have wanted him to.
HARRY: It was my dad. It was my dad who conjured the Patronus.
Hermione attempts to delicately tell Harry that his father his dead. He knows that. And she knows that he knows that. But she's concerned that her friend is becoming delusional and imaging that his parents are still alive.
SIRIUS: I expect you're tired of hearing this but you look so like your father. Except your eyes. You have.
HARRY: My mother's eyes.
Considering Harry misses his parents so much, he probably doesn't ever tire of hearing it, especially because they were good people. He wants to live up to their expectations.
SIRIUS: It's cruel that I got to spend so much time with James and Lily, and you so little. But know this: The ones that love us never really leave us. And you can always find them in here.
Sirius parts with a little bit of greeting-card wisdom, but it's important for Harry to hear it. He doesn't need to pretend that his father is still alive in order to remember him. And as Harry proves with his own bravery, his father lives on within him.
[Harry inflates his aunt.]
We're not sure what spell Harry uses to inflate his aunt. He does it without saying anything or using a wand. Although it's satisfying (because Marge is so freaking awful) it makes Harry seem almost like Carrie, unable to control his abilities. Don't take Harry Potter to the prom…yet.
STAN SHUNPIKE: Muggles? They don't see nothing, do they?
Do they? We're not sure. We seem to still be figuring out this world's rules of magic three books in. One continuity error here is that a flying car was seen by Muggles in the previous book.
MINISTER: She has been properly punctured and her memory modified. She will have no recollection of the incident whatsoever.
Because wizards aren't supposed to do magic outside of Hogwarts, Harry could be in a pile of deep doo-doo-flavored Bertie Botts jellybeans for inflating Aunt Marge. It's handy that wizards and witches have a Men in Black-like ability to erase memories. Erasing her memory means Harry gets off without punishment…this time.
RON: Where did you come from?
HERMIONE: Me? I've been here this whole time.
Hermione has always been a good student, but she's suspiciously good this term. She's in almost every class, showing up seemingly out of nowhere in her seat. Hermione's behavior is weird even by Hogwarts standards, and it makes Ron and Harry (and us!) wonder what she's up to. And if she keeps sneaking up on people like this she'll need to wear a bell.
RON: Hang on. That's not possible. Ancient Runes is in the same time as Divination. You have to be in two classes at once.
HERMIONE: Don't be silly. How could anyone be in two classes at once?
First of all, what magic is Ron using to actually be observant for once? And second, by the time Hermione says this, we're absolutely positive that she's in two classes at once, but we just don't know how she's doing it yet. We will eventually be introduced to a new magical artifact, the Time Turner.
HERMIONE: An Animagus is a wizard who elects to turn into an animal. A werewolf has no choice. With each full moon he no longer remembers who he is. He'd kill his best friend. Furthermore, the werewolf only responds to the call of its own kind.
Because werewolves don't actually exist (at least that's what they want you to think!) a work of fantasy needs to build its own lore about the creatures. Harry Potter's werewolf lore is fairly traditional, down to the full moon and the uncontrollable behavior.
DUMBLEDORE: Mysterious thing, time. Powerful, and when meddled with, dangerous.
Tension is increased at the end when Dumbledore tells us that time magic isn't something that happens on a regular basis. Blowing people up to four times their original size: yes. Time travel: not so much.
MARGE: Damn good of my brother to keep you. He'd have been straight to an orphanage if he'd been dumped on my doorstep.
The Dursleys seem to be taking out their frustrations and anger at Harry's mother on Harry himself. They should get in touch with Snape, because he has the same M.O.
UNCLE VERNON: You bring her back! You bring her back now. You put her right!
HARRY: She deserved what she got.
Harry also acts impulsively and lashes out at people who anger him (like when he inflates Aunt Marge, for example) perhaps for good reason. But Harry is also thirteen, so we cut him some slack. For the adults who act this way—Vernon Dursley in this example, and Snape later on—we're all out of slack. They should know better.
MR WEASLEY: When you stopped You-Know-Who, Black lost everything. But to this day, he still remains a faithful servant. And in his mind you are the only thing that stands in the way of You-Know-Who returning to power. And that is why he has escaped from Azkaban. To find you.
By this point, it seems like every adult wants to take revenge on Harry Potter simply for being born. Can't these people just move on with their lives?!
MALFOY: Wait until Father hears Dumbledore's got this oaf teaching classes.
Malfoy is a jerk through and through. He seems to dislike Hagrid just because he's a friend of Harry's. And Malfoy will take any opportunity to hurt Harry, even if it means hurting his friends.
HARRY: He was their friend and he betrayed them. He was their friend! I hope he finds me. Because when he does, I'm gonna be ready! When he does, I'm gonna kill him!
Once again, we see Harry willing to commit an act of revenge against someone who hurt his parents. How does this make Harry any different from the person he fears Sirius Black to be?