How we cite our quotes: Chapter.Paragraph or Chapter.Section.Paragraph (depends on whether or not the chapter had sections - some did not)
Quote #10
Professor Snape is here at school with us. [...] Sirius here played a trick on him which nearly killed him, a trick which involved me –"
Black made a derisive noise.
"It served him right," he sneered. "Sneaking around, trying to find out what we were up to [...] hoping he could get us expelled [...]" (18.55-7)
Sirius's idea of justice could use some adjustment. It's really interesting that he says essentially the same thing about Snape as he later does about Peter. He has nothing but contempt for people who "sneak" around and try to cause problems for others.
Quote #11
"See here, Snape, be reasonable," said Fudge. "This door's been locked, we just saw –"
"THEY HELPED HIM ESCAPE, I KNOW IT!" Snape howled, pointing at Harry and Hermione. His face was twisted; spit was flying from his mouth.
"Calm down, man!" Fudge barked. "You're talking nonsense!" (22.1.36-8)
It's fitting that Snape gets a taste of his own medicine here. He's usually horribly unfair to everyone else, so it's fitting that he gets to experience an unfair situation too, where he basically gets screwed over.
Quote #12
Black and Lupin were looking at each other. Then, with one movement, they lowered their wands.
"You're the only person who has the right to decide, Harry," said Black. "But think [...] think what he did [...]"
"He can go to Azkaban," Harry repeated. "If anyone deserves that place, he does [...]" (19.175-7)
Harry's phrasing here is very interesting. He refers to Azkaban as "that place," implying that it's truly awful. But he decides that Peter really does deserve it, even if no one else really does.