Commonly regarded as an epitome of a budding bureaucrat, the plain looking Feargus is the receptionist of the Hall of Congress in NCR. Sometime before 2241, he was coerced by Darion into spying on the Republic forces and deliver monthly reports to him, so that the New Khans could organize a valid resistance. The reports contained monthly production totals, caravan schedules, security rosters, minutes of Congressional hearings, secret council reports, diplomatic correspondence from New Reno, Redding, and Vault City, even several weeks worth of President Tandi's appointment schedule.
He did realize the dangers of working on two fronts, however, and wouldn't miss Darion if he had a fatal accident.
By acquiring the NCR Spy Holodisk, the Chosen One can expose Feargus' dealings with the Khans to president Tandi for an ample reward. Feargus leaves the Congress building immediately and it's not known what happens to him afterwards, although it's likely he was arrested and executed for high treason.