O. Henry’s writing style in “After Twenty Years” consists mainly of dialogue between the characters, interspersed with short, unadorned descriptions of the setting and movement of the characters through the New York City streets. The following passage—which comes as “Jimmy” (who is really a plainclothes police officer) and Bob reunite after 20 years—captures one such moment of narratorial intervention:
The two men started up the street, arm in arm. The man from the West, his egotism enlarged by success, was beginning to outline the history of his career. The other, submerged in his overcoat, listened with interest.
At the corner stood a drug store, brilliant with electric lights. When they came into this glare each of them turned simultaneously to gaze upon the other’s face.
In this passage, the narrator shifts away from dialogue between “Jimmy” and Bob, describing the way the two men move together up the street, Bob “outlin[ing] the history of his career” and “Jimmy” “listen[ing] with interest.” O. Henry’s writing style is quite simple and unadorned here, as is true throughout the story. While some of his work is more lyrical, in this story O. Henry’s narrator mirrors the simple and conversational way in which the characters speak.
That said, in the second part of this passage, O. Henry intentionally increases the dramatic tension (and makes his prose slightly more poetic) by having the men walk by a drug store that is “brilliant with electric lights.” This creates the opportunity for Bob to finally see that this man is not Jimmy after all, but a police officer pretending to be Jimmy in order to arrest him.