R. Langston was a scientist working for the Vault-Tec Corporation at Nuka-World before the Great War. He was stationed at test number two, Subliminal Suggestions Tech, using holodisks to sent people subliminal messages to get them to do weird things, like taking off their clothes or running around and screaming. The terminal entries on J. Hodgson's terminal show signs that Langston also used this technique on colleagues.
He sat in the same room as C. Grunner. As with the other employees, Grunner and Langston were also unwillingly used as a test subject. When the bombs fell, Langston stormed into their office to warn Grunner, after which he was shot by him.