Fairbanks was a Paladin, now lying dead in Black Mountain crater, in 2281.
Fairbanks, along with Paladin Hughes, were given the duty of finding parts for the bunker at Black Mountain, and to ask the super mutants and their kin.
The super mutants, as you can guess, weren't any help at all, and killed Hughes and Fairbanks. Both bodies lie in a crater on the way to the top, serving as food for the nearby centaurs.
Fairbanks appears only in Fallout: New Vegas.