At the beginning of chapter 10 of Gary Paulsen's Hatchet, the writer uses personification to illustrate the importance of the new-found fire in Brian's life. The fire gives Brian great joy:
"It was precious to him... the happy crackle of the dry wood as it burned"
It also creates a new demand on his time, and for the next day the problem constantly demands his attention:
"...he could never leave it. He went to the trees and brought in as many dead limbs as he could chop off and carry... and broke them in small pieces and fed the fire."
The personification of the fire serves to highlight Brian's loneliness. Although Brian's thoughts seem to indicate the fire needs constant care, most readers know that a campfire can be left unattended for some time without any harm being done; in fact, the fire burns down to embers during the night and Brian is able to rekindle it. It's more likely that Brian is the one who needs constant companionship and attending.
Similarly, the personification of the fire shows how fragile and vulnerable Brian believes himself to be. He guards and feeds the fire at every opportunity, simply because he cannot do the same for himself.