Describe the character of Patrolman Wells in "After Twenty Years."

Patrolman Wells' character is revealed through his actions and words at the beginning of the story, through Bob's statements about him, through his note at the end of the story, and by reading back into the story things that are not revealed until the end of the story.

The unnamed officer on his beat at the beginning of the story is Jimmy Wells. Jimmy is described as having a "stalwart form and slight swagger." "Stalwart" means loyal, reliable, and hardworking. Although O. Henry uses the word to describe his "form," readers understand the word applies to his behavior. Still, Henry spends a great deal of time describing the appearance of Wells on his beat, showing that he is a conscientious and confident policeman. When Wells is speaking with the man who is waiting for his friend, Wells seems inquisitive yet polite and friendly. Readers have a perception that the officer is professional yet personable as he converses with the stranger and then makes his way down the street. 

Bob reveals several things about Jimmy: that he "was the truest, staunchest old chap in the world," completely trustworthy, loyal to his hometown, a good fellow, but "a kind of plodder." This could be taken to mean that he was not one to try get-rich-quick schemes but would work hard and persistently to achieve his goals.

In Jimmy's note, he reveals that he was at the meeting place on time; he recognized Bob's face as a man wanted by the police in Chicago; and he couldn't bring himself to arrest his old friend personally, so he arranged to have a fellow officer do it. This shows that Jimmy is dependable, perceptive, upright, loyal, and concerned for his friend's feelings.

Finally, readers can take what they find out at the end of the story about Jimmy and make additional conclusions about him. He is indeed very professional as a patrolman; he takes nothing for granted and puts his job as a law enforcement officer above his private interests. The fact that he didn't let Bob know he was Jimmy from the moment he saw him in the doorway suggests that Jimmy is very careful or that perhaps he already suspects that his friend is "Silky Bob." If the description of the wanted man was enough to tip Jimmy off even before he saw his friend, then that may explain why he didn't identify himself until Bob lit a match and revealed his face. When his identity was confirmed to Jimmy, Jimmy kept talking without revealing any surprise or emotion. This again shows that Jimmy is an astute officer, able to put the safety of the community above his own feelings. He obviously had to prepare the "plain-clothes man" well to ensure that Silky Bob went along with him, making the arrest safe for both of them, again showing intelligence and foresight. 

To get a full understanding of Patrolman Wells' character, one has to take what is learned at the end of the story and then go back through the story again with that knowledge. Doing that will reveal additional layers of how professional and impressive Wells is as a patrolman.