Captain Beatty can be directly characterized as the antagonist in "Fahrenheit 451". An example of this is how Captain Beatty disapproves of Montag's actions. Beatty disapproves of Montag's curiosity of books, when he himself was also curious at one point. He brings Montag down, with all of his accusations, and eventually forces Montag to set fire to his own house.
Captain Beatty can be indirectly characterized as intimidating in "Fahrenheit 451". An example of this is when Montag and Mildred start to worry that Captain Beatty might be at the door. They are worried because they don't know what he will do if he comes in, they were scared. Beatty was very intimidating when he forced Montag to burn his house down and when he set the hound on Montag. Also, when he hinted at the fact that he might have had something to do with Clarisse's death.