Watch. Leon's early time in prison, getting accustomed in particular to the food slot.
It was cruel, the rectangular slot in the door that they allowed him. Leon shifted in his chair, which he placed so that he could stare straight out the slot. People walked by intermittently, fellow inmates flanked by guards; each had his own door with its own little peep hole, and if ever one did catch another's eye they both knew what the other felt. The slot was a mail box of sorts, through which everyone would receive only a glimpse of their fellow men; nevertheless a glimpse received with vigour, the sole gift of their isolation from each other and the world. Convicts at least are free to walk around and see the sun. But Leon wasn't a convict; the men around him weren't convicts, and he doubted that any of them would ever get to receive the pleasure of sunlight again.
He thought a little more. Perhaps they had given the slot as a sort of peep show, of the type that lewd men with money and time would indulge in back outside. Leon was plenty lewd, with time stretched out before him, but the people who passed by weren't his type, nor did the parts he could see convey anything of the erotic sort. Other inmates he guessed had long given up on the prospect of beautiful women and instead hoped for love among their fellow dregs of humanity. He was only different because he hadn't been there for long. But at any rate, all dreams of intimacy were just that no matter the preference. If it weren't for that damned slot…
Leon started. He had fallen asleep in his chair. What he first saw was the slot. Darkness except for the faint glow of some light in the hallway. How long he had been asleep was unknown, but long enough to make his neck stiff. He turned his head to the left and heard something crack. Sight was a problem too; Leon's eyes ached, and his peripheral vision was blurry. Focusing on a wall, he could see the blurry outline of a rectangle floating around faintly. Now I have square eyes…or is that oblong? He tried batting away the floating shape just for the sake of it; it didn't leave, or even react to his hand. Whether or not that was a relief was debatable; did Leon want his faculties in order, or did he want to lose himself in the relative bliss of insanity?
Climbing into the lumpy prison bed, he decided that the slot was a clever kind of torture device, never mind its practical functions. And as for his sanity, it was a topic worthy of pondering at a later date.
Leon's not my regular sort of character to write on. I just felt like writing this for some reason.
The Last Day of a Condemned Man by Victor Hugo provided the first thought. Good book. Read it.