Who is Old Bryson in "One Thousand Dollars" by O. Henri?

Old Bryson is the rather brusque and vinegary member of the men's club that young Gillian frequents.
Old Bryson is really not old; at forty years of age, he is simply one of those anti-social men who join social clubs so that they can sequester themselves in dark corners and be exasperated by others. While they pretend to be absorbed in their reading, they listen to a great deal, and know about many of the members.After the death of his guardian, who leaves him one thousand dollars, Gillian comes to his club to ask Old Bryson what he should do with this inconvenient amount of money.

"I thought," said Old Bryson, showing as much interest as a bee shows in a vinegar crust, "that the late Septimus Gillian was worth something like half a million." ("One Thousand Dollars")

Demonstrating that he is not unlike Bryson in his cynicism, Gillian "assents joyously" to Old Bryson's remark. "...and that's where the joke comes in." He tells Bryson that his uncle has left most of his money to science for the invention of a bacillus and the rest to "establish a hospital for doing away with it again" ("One Thousand Dollars"). The butler and the housekeeper get a seal ring and $10 each, and he gets $1000.00.
No longer disinterested, Bryson reflects that Gillian has always had copious amounts of money to spend. Gillian concurs, "Uncle was the fairy godmother as far as an allowance was concerned" ("One Thousand Dollars"). And, when Bryson asks if there are any other heirs besides Gillian, the young man replies, "None." He tells Bryson about a ward of his uncle, a Miss Hayden, who lives in the house. But, she also has only received $10 and a ring. Finally, Old Bryson rubs his glasses and smiles, and Gillian knows that he will be more offensive than usual.
Bryson finally suggests that Gillian spend the lump sum on a Miss Lotta Luriere, who works at the Columbine Theatre. Then, he tells Gillian, he can "inflict" his presence on a  sheep ranch in Idaho. "I advise a sheep ranch as I have a particular dislike for sheep," says Bryson ("One Thousand Dollars"). Gillian rises, thanks Bryson and heads to the theatre, resolving to rid himself of his inheritance.