The larger theme in "The Ransom of Red Chief" is one that O. Henry used in some of his other stories. It is best expressed in the adage "Crime does not pay." The narrator opens the story this way:
It looked like a good thing: but wait till I tell you.
Bill and Sam expect to get two thousand dollars as ransom for the wildcat boy they kidnap. Instead they end up paying his father two hundred and fifty dollars just to take him off their hands.
In O. Henry's story "After Twenty Years" the author contrasts two old friends who have led different lives. Jimmy Wells has become a policeman and is content. No doubt he has a wife and children and a nice home. He has a steady job and can look forward to a regular pension for the rest of his life when he retires. 'Silky' Bob has become a crook and has apparently made a lot more money than Jimmy; but he had been on the run all his life and has missed out on the truly important things in life, including a home and family and a circle of good friends. He has an abnormal existence with no security and the constant threat of being arrested. At the end of the story, Bob is being taken off to jail and may have to serve a long prison sentence after he gets to Chicago.
In O. Henry's well-known story "A Retrieved Reformation" the hero Jimmy Valentine is a successful and notorious safecracker. But he falls in love and goes straight. He realizes that "Crime does not pay," and that "Honesty is the best policy" after he falls in love with a lovely small-town girl who sincerely believes in him. He writes to an old pal as follows:
Say, Billy, I've quit the old business—a year ago. I've got a nice store. I'm making an honest living, and I'm going to marry the finest girl on earth two weeks from now. It's the only life, Billy—the straight one. I wouldn't touch a dollar of another man's money now for a million.
Jimmy will not be making spectacular hauls of stolen money, but he will have a peaceful life, a good reputation, stability, a beautiful wife, a home, and no doubt a number of children. Criminals like Sam and Bob in "The Ransom of Red Chief" are always on the run. They have to be. When they make a little money they have to use it to flee the scene of their latest crime. They have been petty con men for years, but we see them driving an old car and sleeping on the ground.
O. Henry was a pen name. The author was afraid to use his real name because he was hiding from his past. He served over three years in a state prison for embezzlement. He knew from personal experience and from observation of the many criminals he met in prison that crime does not pay and that honesty is the best policy.