Ray Bradbury’s use of personification in the early pages of Fahrenheit 451 consists mainly in a long description, stretching over several pages, of the fire station’s Mechanical Hound. Page numbers vary among different editions.
When Guy Montag returns to his fire station the day after Mildred’s overdose and treatment, he encounters and talks to the Mechanical Hound. This robot is described at length in the section that begins
The Mechanical Hound slept but did not sleep, lived but did not live.
The robot is primarily compared to a dog, the animal on which it is largely modeled, but it has eight legs. However, some of its characteristics seem to be human. When Montag touches the sleeping hound’s muzzle, it looks at him and growls, then seems about to stab him with its built-in, retractable syringe. Montag is alarmed at the simmering growl and hostile look.
On the other floor among the men, he tells the captain, “It doesn’t like me.”
Incredulous, the captain insists: “It doesn’t like or dislike. It just ‘functions.’”
Montag speculates that someone has been tampering with the hound, altering the chemical balance of its memory. He tells the captain this theory and notes how the beast reacted: “Irritated, but not completely angry.”
Montag continues speculating about the mechanical beast, referring to it in increasingly human ways. As he considers its thoughts and knowledge, it bothers him that predatory, lethal behavior constitutes the limits of that knowledge.
What does the Hound think about down there nights? ... All we put into it is hunting and finding and killing. What a shame if that’s all it can ever know.