Natalia Dubrovhsky is a premade character in Fallout. She is designed to not even meet The Master at all, but to sneak in and detonate the nuke in The Cathedral.
She is the grandchild of a Russian diplomat who worked at the Soviet Consulate in Los Angeles. She is also a talented acrobat, with excellent coordination and reflexes. She is extremely intelligent and resourceful. Her only difficulty as a young child was understanding personal property laws. Natalia is very interested in leaving the Vault, and curious to explore the outside world.
Interestingly, her biography and a couple of plaques in Museum of Technology in Fallout 3 are the only places where the Soviet Union is ever mentioned in any of the Fallout games.