What is the character of Patrolman Jimmy Wells?
Patrolman Jimmy Wells is described from two perspectives: that of the anonymous third-person narrator and that of "Silky" Bob as he remembers Jimmy from twenty years earlier when they were close young friends. From the narrator's perspective, Jimmy is a typical New York City beat cop. He appears to have been on the beat for many years. His behavior is typical of beat cops in general. He seems to be happy in his job. He enjoys his social status. He enjoys the responsibility of holding up his corner of the world. The narrator achieves the effect that O. Henry wanted to create when he says:
... the officer, with his stalwart form and slight swagger, made a fine picture of a guardian of the peace.
O. Henry is not enlightening but deceiving. This is another way of saying that the officer looked like a typical New York cop. That is the way the reader imagines him during his conversation with Bob: as a big stranger in a navy-blue uniform which blends into the dark background of the deserted city street. O. Henry wanted to introduce him to the reader without revealing that he was Jimmy Wells, the man "Silky" Bob was waiting for. The reader is as much deceived as Bob. After their conversation in the hardware store doorway, Jimmy goes on his way without the reader's slightest suspicion that he was Bob's old friend. Bob has no such suspicion because Jimmy has aged, and Bob never would have expected Jimmy to become a cop. The reader can see how the passage of twenty years has changed Bob's character, but the reader does not realize until after the proxy arrest how much Jimmy's character has been affected by the same passage of time.
Bob describes Jimmy to Jimmy without realizing who he is talking to.
"But I know Jimmy will meet me here if he's alive, for he always was the truest, staunchest old chap in the world. He'll never forget."
From the narrator's description of Jimmy's appearance and from Bob's description of Jimmy's character, we get the impression that Jimmy is a conservative, conventional, middle-aged man who obeys all the rules by the book. He would not be at all likely to let his old friend avoid arrest. Doing so would be out of character. He can't bring himself to arrest Bob personally after he realizes that his old friend is wanted by the Chicago police, so he has a fellow officer perform that task for him. Jimmy did not have an internal conflict over whether to arrest Bob; Jimmy had to see the arrest performed regardless of his personal feelings. The fact that Bob spoke so highly of him was probably responsible for Jimmy's ultimate decision not to make the arrest himself.