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Хагрид - 3 кн.
They had never heard Hagrid talk about his brief spell in Azkaban before. After a pause, Hermione said timidly, “Is it awful in there, Hagrid?”
“Yeh’ve no idea,” said Hagrid quietly. “Never bin anywhere like it. Thought I was goin’ mad. Kep’ goin’ over horrible stuff in me mind… the day I got expelled from Hogwarts… day me dad died… day I had ter let Norbert go…”
His eyes filled with tears. Norbert was the baby dragon Hagrid had once won in a game of cards.
“Yeh can’ really remember who yeh are after a while. An’ yeh can’ really see the point o’ livin’ at all. I used ter hope I’d jus’ die in me sleep.

Сириус - 3 кн.
“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… helped me keep my powers… so when it all became… too much… I could transform in my cell… become a dog. Dementors can’t see, you know…” He swallowed. “They feel their way toward people by feeding off their emotions… They could tell that my feelings were less—less human, less complex when I was a dog… but they thought, of course, that I was losing my mind like everyone else in there, so it didn’t trouble them. But I was weak, very weak, and I had no hope of driving them away from me without a wand…

Корнелиус Фадж про Сириуса - 3 кн.
Yet I met Black on my last inspection of Azkaban. You know, most of the prisoners in there sit muttering to themselves in the dark; there’s no sense in them… but I was shocked at how normal Black seemed. He spoke quite rationally to me. It was unnerving. You’d have thought he was merely bored—asked if I’d finished with my newspaper, cool as you please, said he missed doing the crossword. Yes, I was astounded at how little effect the Dementors seemed to be having on him—and he was one of the most heavily guarded in the place, you know. Dementors outside his door day and night.”

Про Барти - 4 кн.
“That’s right,” said Sirius, and he didn’t look remotely amused now. “I saw the Dementors bringing him in, watched them through the bars in my cell door. He can’t have been more than nineteen. They took him into a cell near mine. He was screaming for his mother by nightfall. He went quiet after a few days, though… they all went quiet in the end… except when they shrieked in their sleep…”
For a moment, the deadened look in Sirius’s eyes became more pronounced than ever, as though shutters had closed behind them.
"He died about a year after they brought him in.”
“He died?”
“He wasn’t the only one,” said Sirius bitterly. “Most go mad in there, and plenty stop eating in the end. They lose the will to live. You could always tell when a death was coming, because the Dementors could sense it, they got excited.