Character Analysis
One of the first things you learn about Patrick Sonnier is that "after his arrest, while in the parish jail, he had attempted suicide by slitting his wrists" (2.120). He did so, Prejean suggests, out of remorse. In fact, Prejean says that one of Pat's guards told her that "he never saw anyone with more remorse than Patrick Sonnier" (2.118).
Pat committed a heinous, horrible crime. If he did not actually shoot David LeBlanc and Loretta Ann Bourque himself, he participated in kidnapping them, and he helped his brother to kill them. (We never really know for sure what happened.) Nevertheless, the first thing we find out about him is that he seems horrified by what he did, and he feels remorse for it. Now, Lloyd LeBlanc, David's father, says that "all this talk of Sonnier being a rehabilitated man is hard to buy" (3.169), and of course you can't know what Pat would do if he were to have been released, but as far as we can tell, from what Prejean tells us, he seems sincerely regretful.
Pat, then, is what you could call the good Death Row inmate. He's not innocent: he was responsible for the horrible crimes of murder and rape that he's accused of. But he seems, at the least, willing to try to change, and to renounce his crime, if he's given the chance to do so. While in prison, he has had zero, zilch, not a single disciplinary write-up. He even dies without recrimination or hate on his lips. His last words, directed to Sister Helen, are "I love you" (4.226).
Killing Pat seems cruel and pointless in part because it seems clear that he already regrets his crime and has no interest in repeating it or excusing it. His death seems only to be for the sake of revenge—and confused revenge, at that, since Eddie, his brother, may well be the one who fired the bullets, and Eddie faces only life in prison rather than the death penalty. Even Lloyd LeBlanc, we learn at the end of the book, didn't really want Pat dead. Killing Pat just seems to mean more killing; it's hard to see what good it accomplishes.
Pat's Timeline