Bill ends up loathing and terrified of little Johnny, the boy they kidnap. He is willing to do almost anything to get him off his hands. The humor and irony in the story turn on what looks like an easy money kidnapping becoming far more than the hapless kidnappers bargained for. At the beginning of their adventure, the twosome:

figured that Ebenezer would melt down for a ransom of two thousand dollars to a cent.

From the start, however, Johnny is a handful, pelting Bill in the eye with a piece of brick and putting up a fierce fight against being taken. Yet rather than being frightened, Johnny, who is pretending to be an Indian chief, thinks the kidnapping is a game. He thinks he is going camping. He has no sense he is in any real danger, and he wears Bill down with his antics to the point that Bill experiences utter exhaustion.

By the end of the story, when the father, Ebenezer, refuses to pay up, Bill is more than willing to pay him $250 to take the child off their hands. He says it feels like a bargain, asking what is $250 after all?

This story is an example of situational irony, where events unfold opposite from what is expected. One would expect the kidnappers to be in control of the situation, not the child.

Bill cannot stand the boy. Upon kidnapping him, Johnny puts up such a fight that Bill is left putting ointment on his wounds. Johnny, "Red Chief," is having so much fun terrorizing Bill and pretending he is camping that he doesn't even want to go home. Bill takes the brunt of most of Johnny's energy. Not only is Bill exhausted and beat up, but he is mentally worn out. Eventually, he becomes afraid of Red Chief. Sam notes, "That boy had Bill terrorized from the start." 

Sam awakens the day after the kidnapping to hear Bill screaming like a woman. Johnny was "industriously and realistically trying to take Bill’s scalp." Sam gets the knife from Johnny and adds that "Bill's spirit was broken." Bill won't even sleep because he is legitimately afraid of what Johnny might do. Bill even tries to send Johnny home before they hear from Ebenezer about the ransom. By the end, Bill is so terrified and exhausted that he doesn't mind paying to have Johnny sent back home.