| Quote #7
"I don't know how I did it," he said slowly. "I think the only reason I never lost my mind is that I knew I was innocent. That wasn't a happy thought, so the Dementors couldn't suck it out of me [...] but it kept me sane and knowing who I am [...] (19.124)
Sirius finds a sort of freedom in his own efforts to remain sane. It seems like freedom boiled down to keeping a hold of his sense of self, which is probably still true outside of Azkaban.
| Quote #8
"I must admit Peter, I have difficulty in understanding why an innocent man would want to spend twelve years as a rat," said Lupin evenly. (19.104)
Again, we see another kind of imprisonment, and another example of imprisonment by choice. Also, kudos to Lupin for being this book's breakout comedic star.
| Quote #9
"Well, in that case, Potter, you'll understand why I don't think it's a good idea for you to be practicing Quidditch in the evenings. Out on the field with only your team members, it's very exposed, Potter –." (9.2.8)
Harry is frequently confined to the school or closely monitored during this book.