O. Henry's stories typically contain ironic reversals that come at the end of a narrative that is constructed upon the basis of some incongruity, and "One Thousand Dollars" clearly fits this pattern. For, the protagonist, Bobby Gillian, the heir presumptive of a fortune from his wealthy uncle appears to be an idle, selfish, and irresponsible young man. When, for instance, he sits by "Old Bryson,...calm and forty and sequestered," at the gentlemen's club to which he belongs, the man is less than eager to talk to him. Then, after Gillian asks him several times how he can best spend one thousand dollars, Bryson gives him the flippant suggestion that he buy his showgirl, Miss Lotta Lauriere a diamond necklace, a suggestion that indicates Gillian's character as a spendthrift and one who does not associate with worthy company.
And, although Gillian does go to the young woman in question and ask her, she gives him little attention and merely "carols" his offer, "Just as you say." So, he departs and once in the cab asks the driver what he would do with a thousand dollars. Finally, he decides to pay a visit to Miss Hayden, a ward of his uncle and daughter of the uncle's deceased friend. Gillian tells her that there was a codicil to the will bequeathing her $1,000, and he hands her the money, declaring at the same time his love for the young lady. Politely, Miss Hayden rejects his offer of love.
It is at this point that the reader now finds Gillian more a generous romantic than a ne'er do well. Further, when he brings his required report of his dispersal of the money, the lawyers inform him that if he has performed an unselfish act with the money, the uncle has instructed them to provide him with $50,000 as an inheritance, Gillian, surprisingly, snatches the envelope away from the lawyer Tolman and tears into pieces, saying that he has itemized his losses at the races and quickly bids them good-bye.
This surprise ending demonstrates a goodness and generosity never known to Gillian; truly, he has a generous and loving heart, after all.
True!But actually, on gaining info that Gillian gives his money selflessly to this woman Miriam , all that changes of our opinion about Gillian is that he is actually a kind boy, good at heart -although not so much in habits- who is selfless, and that he is wanting to repent for all the money that he has wasted.
However, on realizing how Gillian tears the document depicting his expenditure, we realize that his intention might never have been to change his habits, but just an act of affection, unconditional and selfless -probably love- an affection that is further glorified by how he, at the drop of a hat, without haste, tears up the document that would have enabled him to inherit the $50,000 , so that the woman he loves might gain it.
Gillian might after "whistling" through the hallway , have made his way to the racetrack to place a bet.