Answer:
Eckels is a pompous blowhard. That might be not be technical enough, but it is how I would describe him. Perhaps a better character description of Eckels would be to describe him as an arrogant coward. Right from the beginning of the story, Bradbury paints Eckels as a guy that the reader takes an aversion to.
I remember this when I we were talking about it in English 3 months ago.