The principal theme of O. Henry's "Hearts and Hands" is the deceptiveness of appearances. The story neatly expresses this theme when Miss Fairchild sees two men, one of whom is a handsome member of her own class, whom she knows socially, the other a rough-looking man whom she has never met.

It is not Miss Fairchild's fault that she assumes Mr. Easton is the marshal and his companion is the criminal. She does not notice the handcuffs until he draws attention to them, and there is an indication in the text that her first impulse is to think that Mr. Easton is the felon, since her eyes express "bewildered horror." However, the other man quickly tells her that it is he who is the criminal.

The role reversal here is satisfyingly complete. Mr. Easton is revealed, to the reader, though not to Miss Fairchild, as the plausible criminal. Meanwhile, the marshal, who does not appear to be from an exalted social background, is shown to be a man of unusual tact and delicacy. He realizes the shame it would cause Mr. Easton to be exposed in front of Miss Fairchild and carefully provides him with an opportunity to save face and to leave without her guessing the truth. This clearly shows that excellent manners and magnanimity are not the preserve of the upper classes and that the marshal's rough appearance is just as deceptive as Mr. Easton's polished persona.

In "Hearts and Hands," O. Henry sets out to satirize the manners, mores, and customs of the upper-classes. Miss Fairchild is an old acquaintance of Mr. Easton; they come from the same elite background, and previously moved in the same social circles. So when she catches up with him again on a train while he is handcuffed to a rather rough-looking man, she automatically assumes that he's the marshal. The thought that he could be a convicted criminal doesn't cross her mind for a moment.

Miss Fairchild's reflexive snobbery probably helps to explain why Mr. Easton has proved to be such a cunningly plausible criminal for so long. In the past, many people like her have been suckered into his various schemes due to his suave good looks and impeccably polished manners.

The story doesn't simply explore the gap between appearance and reality; it also shows us the excessive value placed upon appearances—of clothes, accent, social graces—by the American upper-classes. 

In many of his stories, O. Henry holds the universal romanticized wish that people are intrinsically good and unselfish. This wish is exploited in the short story "Hearts and Hands." In fact, the title of this story suggests the theme that people will display "heart," or kindness, for others with no self-interest.

After they are seated across from the pretty young woman, the glum-faced man identifies the younger man handcuffed to him as the marshal. Miss Fairfield, who has recognized this younger one as one of her society, is relieved to know that he is no prisoner.

This glum-faced man asks Miss Fairfield to entreat the marshal to speak on his behalf when they reach Leavenworth prison. But, that it is he who possesses an unexpected kindness becomes known only in O. Henry's ironic reversal. For, two other passengers remark upon what has occurred with the interchange of the pretty young woman and the two men who are handcuffed together. The one, who has overheard the glum-faced man identify the younger man as the marshal, remarks to the other about the kindness of this man:

"That marshal's a good sort of chap. Some of these Western fellows are all right."

 "Pretty young to hold an office like that, isn't he?" asks the other man.

The first one exclaims with disbelief,

"Young!...didn't you catch on? Say--did you ever know an officer to handcuff a prisoner to his right hand?"

Ironically, it has been the glum-faced man who is the marshal. But, he has extended kindness and "heart" to his prisoner by pretending to be the convict who is going to prison.

"Hearts and Hands" is a wonderfully ironic story by O. Henry. In the story, a passenger on a train in Denver named Miss Fairchild is seated across from an old acquaintance named Mr. Easton. She notes that Mr. Easton is handcuffed to an older, less attractive man, and the less attractive man asks her to intervene with the marshal, indicating Mr. Easton. Miss Fairchild believes that Mr. Easton is a marshal, a man of the law, and they have a conversation about old times. In the end, strangers on the train note that a marshal would never handcuff a man to his right hand. In other words, Mr. Easton is the prisoner, and the other man, older and heavier, is the marshal.

The theme of the story is that appearances can be deceiving. Miss Fairchild believes that her old friend must be a marshal because she knows him and because he is young and attractive. However, the reality is quite different, as he is a prisoner. O. Henry suggests that people often jump to conclusions that aren't true.