The present specification discloses a locking fastener that includes a first threaded fastener axially positioned within an axial through hole of a second threaded fastener, and captured therein by a rotating joint that permits rotation of the first threaded fastener and the second threaded fastener relative to one another about a common thread axis. In one or more embodiments, the first threaded fastener thread handedness is opposite to the second threaded fastener thread handedness. Additionally disclosed, is a screwdriver tool configured to simultaneously engage and oppositely rotate the first threaded fastener and the second threaded fastener into a mating component having a first mating thread and a second mating thread configured to receive the first threaded fastener and the second threaded fastener, respectively, driven at the same axial advance distance for each turn. Once tightened, the present locking fastener resists loosening and provides a tamper-resistant hold.