DUMBLEDORE: Let's leave the baby with the last people in the world who should raise him. I call him Moses, but they'll probably name him Harry Potter.
HAGRID: So, why THESE Muggles?
DUMBLEDORE: I'll tell you in five books' time.
HARRY: Great. I've got a paranoid uncle, a fatass brother who's fat AND an ass, and an aunt. And they won't let me read my favorite book, Roald Dahl's "Matilda". My life is so Cinderella. So where's my fairy godmother?
HAGRID: (breaks down door) Hello, Harry!
HARRY: ... nothing in my life is fair.
HAGRID: I brought your birthday cake.
HAGRID: Also, you're a wizard.
HARRY: Mpmh mm mzzrm?
HAGRID: Give your fatass brother that cake and let's get you some school supplies.
OLLIVANDER: I guarantee I can find the perfect wand for you. If I can't, you can blow up my shop!
HARRY: Sounds good to me! (does so)
OLLIVANDER: How about this one, the counterpart to You-Know-Whose wand?
HARRY: I-Don't-Know-Who. Nobody tells me anything.
HAGRID: That's because, if you knew anything, your life wouldn't be in half as much danger. Think of it as building character, magical skill, and frequent patient points at Madame Pomfrey's infirmary.
RON: Here's the Hogwarts Express.
HERMIONE: The founder had a real acne problem.
HARRY: Wizard candy is weird. And your pictures move.
RON: For the world's most famous wizard, you sure don't know much about wizards.
NEVILLE: Ah-choo! (something random explodes)
DRACO: Hairy Potty, is it? I'm going to be your rival and enemy because I'm a colossal jerk and got sorted into the evil house.
CRABBE: Huh huh huh. "Potty."
GOYLE: Heh heh heh. "Snake."
MCGONAGALL: Albus, why DO we have an evil house, anyway?
DUMBLEDORE: We couldn't very well turn out evil wizards without one, could we? That's part of our function too... keeping things interesting.
MCGONAGALL: Is that why we keep vital secrets from the students?
DUMBLEDORE: Time for the feast!
MCGONAGALL: Potter, you'll be the Seeker on our Quidditch team.
OLIVER: Here are the rules of the game. Whichever Seeker gets the Golden Snitch first wins, unless his team is behind by more than sixteen goals. You can ignore everything else.
HARRY: That's... really lame.
OLIVER: How else could we make the one position you play the critical focus of the matches? You think we have the narrative skill to follow seven players?
HARRY: Hagrid had something in his pocket when we went to the bank to check my vault full of gold.
RON: (putting on a cheap robe full of holes) You don't say?
HERMIONE: My incredible intelligence would solve this mystery if my deference to authority didn't compel me to look down my nose at you.
RON: When do you demonstrate your incredible humility?
HERMIONE: As the token brilliant female, I cower in bathrooms to be attacked by trolls when I'm upset!
TROLL: Nose become clean when picked. (faints)
SNAPE: Nice to see first-years defeating dangerous creatures. But because I'm a hardnose, I'm penalizing you.
HARRY: I bet he did it.
RON: Did what?
HARRY: Whatever the plot of this book centers around, he's the bad guy. It's obvious.
RON: Snape's trying to kill Harry under cover of Quidditch!
HARRY: Thanks to that, I won the match.
HERMIONE: Are you sure it's not just because you're the main character?
HARRY: Let's wait a couple of books and see, shall we?
HERMIONE: Told you I'd figure it out! He's after the Philosopher's Stone! But because it had already been destroyed by the time this book was published in America, he had to go for the inferior Sorcerer's Stone instead.
HARRY: And it's all thanks to these collectible chocolate cards. I knew eating candy was good for me.
QUIRREL: I'll help you, because I'm such a coward and a friendly guy that I have to be on your side.
HARRY: Good point. We'll tell you everything we know.
HERMIONE: Now we know how to get past the first obstacle in what's undoubtedly a long, complicated path to keep people out. Let's go get the Sorcerer's Stone so that we first-year students will be the only thing keeping You-Know-Who -
HARRY: You mean Voldemort?
HERMIONE: Just ignore the man-eating plant. We're kids.
RON: I'll make myself a pawn sacrifice so you guys can get through!
HERMIONE: I won't sacrifice myself heroically, but I will wish you luck, Harry.
HARRY: Professor Quirrel? You were Voldemort (everyone shudders) all along?
VOLDEMORT: Yes! And once I figure out this last puzzle, I'll come back to life for real!
HARRY: I got it! You needed a pure heart to get the stone.
VOLDEMORT: Damn! And I'd put "gut Neville Longbottom" on my to-do list too!
SNAPE: You know, if you meddling kids hadn't interfered, I'd have saved you long before now.
HARRY: You know, not only did Voldemort (everyone shudders) get past all the best defenses our teachers could put together, but a couple of first-years got past all the best defenses our teachers could put together. Are you sure you guys are qualified for this?
DUMBLEDORE: I'll see you next year, Harry. Go back to the Dursleys', where I put you for your protection.
HARRY: YOU put me there? Where's that magic-boosting stone when I need it?
Hope that was entertaining and not too wildly off the mark. I'll try to do the rest at some point.