Over my 12-year prison sentence (with good behavior, it turned into 10), I read a lot. When I was feeling strong and confident, remembering that I was still young and married to a woman I hardly deserved, I tackled the hard stuff, like Martin Heidegger, Robert Musil, and László Krasznahorkai. When I felt down—guilty that, during one week in 2003, I had scared people in downtown New York with my amateur robberies, overwhelmed that I would spend 123 months of my life behind bars—I read the easy stuff. I got lost in J. R. R. Tolkien, Mervyn Peake, and H. P. Lovecraft.

It was during one of those hard times that I met Brown Jenkin. A character in Lovecraft’s short story “The Dreams in the Witch House,” Jenkin is “a small white-fanged furry thing … no larger than a good-sized rat” that haunts a fictional town called Arkham. The creature was meant to frighten readers, especially those who had experience with rodents. As a prisoner, I had a lot of experience with rats, but Jenkin made me laugh.

Around that time, I became tight with a fellow named Red. (His “government name,” as the other inmates called it, was Anthony Jenkins.) After an evening reading Lovecraft, I asked Jenkins if he had a cousin named Brown Jenkin. Without missing a beat, he said he saw him “every morning after mess-hall chili.”

Jenkins was serving a double-digit sentence for strangling his wife after he found out she had slept with their drug dealer. He was in prison during the prime of his life. Somehow, he dealt with both his guilt and his punishment while still smiling and cracking dirty jokes. Of all the difficult things to do in prison, laughing was perhaps the hardest.

When I felt down, I got lost in J. R. R. Tolkien, Mervyn Peake, and H. P. Lovecraft.

After my release, I stayed in touch with Jenkins. When he was freed, a year after me, he went back to work at a supermarket—though no longer as a butcher. When we occasionally spoke on the phone, he still made quips and jokes. One day he texted me just to say he was proud of me. I called him, but he didn’t pick up.

I kept calling until I discovered that his body had been found hanging from a tree. Less than a year after his release, Jenkins had relapsed on crack and committed suicide. The man who amazed me by serving his sentence with a smile on his face didn’t last one year in freedom.

It took me a long time to erase his final message to me. Jenkins loomed over me like Jenkin loomed over Arkham. He’s been on my mind, nuzzling at me in the dark, ever since his death. To end the haunting, I followed Lovecraft’s lead: I wrote about it.

Daniel Genis’s Sentence: Ten Years and a Thousand Books in Prison will be published on February 22 by Viking