Percy Wetmore is a small, prison guard, that does his work in death row out of pleasure to see criminals die. The other guards want him out of the area because of that, but his contacts enable him to stay, where he is. He has a nickname for the big prisoners which he calls lugoon, a combination of lug and goon. He always causes trouble and disturbs the peace in the area through his violent behaviour and, finally, he even sabotages an execution, because he wanted the convicted prisoner to additionally suffer before his death. He succeeds in his quest. He is therefore unofficially punished because of it by the other guards, but shows no remorse in the end.
John Coffey turns him into a tool for his purpose of killing William Wharton for his crimes and in order to punish him for his crime. He never recovers from that, which was also his purpose and ends up in an asylum for the rest of his life.