Character Analysis
"The Lightning-Rod Man" is more a parable than a character-driven story. Which is to say—the characters aren't much. The Lightning-rod man is a pompous charlatan who wants to scare people into buying his lightning-rods, so he goes around in thunderstorms threatening folks with death by lightning if they don't pay up. He's more a finger-wag than a character. His basic purpose is just to stand there so Melville can point at him and say, "don't be that guy."
In order to make sure you don't want to be that guy, Melville makes him just about as unpleasant as possible. He's pushy and bossy and generally unpleasant:
Are you so horridly ignorant, then…as not to know that by far the most dangerous part of house, during such a terrific tempest as this, is the fire-place? (4.14)
How would you like it if you let somebody into your house and they called you "horridly ignorant"? Then on top of that he's sanctimonious and moralistic; when the narrator playfully calls him Jupiter (which, okay, is kind of a jerky thing to do too), the Lightning-rod man tells him not to use the names of pagan gods:
You are profane in this time of terror. (4.19)
And then, at the end, the Lightning-rod man actually physically attacks the narrator. Again, this is supposed to be a parable; the Lightning-rod man attacks so the narrator can break his fork and triumph over human fear. (See Symbol: Lightning-rod.) But if you consider it as characterization, the guy basically assaulted someone for no reason. He's a jerk. Door-to-door salesman from hell.