How we cite our quotes: All quotations are from Harry Potter and the Prisoner of Azkaban.
Quote #1
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.
Quote #2
MARGE: It's all to do with the mother. You see it all the time with dogs. If something's wrong with the b****, 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.
Quote #3
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.
Quote #4
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.
Quote #5
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.
Quote #6
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.
Quote #7
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.
Quote #8
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.
Quote #9
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.
Quote #10
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.