Old Bryson, as he is described by O. Henry, is a gentleman of forty who frequents the men's club. He is important to the story in his role both as a foil to Young Gillian and as a mirror of the cynicism of the younger man, who often talks to him. Thus, Bryson is the instrument which O. Henry uses to begin his development of the main character.
In his role as foil to Young Gillian, Old Bryson represents formal British behavior for a certain part of the upper class in contrast to Gillian's casual indifference. He is "calm" and "sequesters," or isolates, himself in a corner with a book. In his cynicism, which mirrors that of Young Gillian, Bryson probably feigns disinterest in Gillian more than he really feels because he does engage in conversation with the young man. And, it is through this conversation of Old Bryson with Gillian that the reader is informed of both Gillian's personality and the situation upon which the narrative revolves.
After Gillian relates the circumstances of his uncle's will, he says to the older gentleman,
"Don't be superior and insulting, Old Bryson--tell me what a fellow can do with a thousand dollars."
Bryson, who intends to be "more offensive than ever," observes cynically that a thousand dollars, which Gillian inherited and must spend, then report on what he used it for, "means much or little"; then, he provides both generous and selfish examples. But, Gillian criticizes his moralizing, reiterating that he has asked what he, specifically among men, can actually do with the thousand dollars. So, Bryson chuckles and tells the young man that he should purchase a diamond pendant for an actress that is his favorite, then "inflict" himself upon a sheep ranch in remote Idaho because "I have a particular dislike for sheep." Gillian, then, is delighted with this response, and replies with similar cynicism:
"You've hit on the very scheme. I wanted to chuck the money in a lump, for I've got to turn in an account for it, and I hate itemizing."
Young Gillian then departs from the men's club and heads to the Columbine Theatre where he will seek out Miss Lauriere expecting, although mistakenly, to spend the $1,000 on a diamond pendant for her.