Bobby is assigned to work in the reactor room with Old Rusty, but does not complete any of the work himself. He is addicted to Jet, supplied by his sister Tina De Luca which he stashes behind a false panel hiding the door to the observation wing of the vault. When he is not using Jet he is drunk, according to Gwen McNamara's terminal logs. He is also known as Robert De Luca.
Bobby will buy Jet from the Sole Survivor for 75 caps each. If the Sole Survivor sells Jet to Bobby, he may be later found dead in his room making him unavailable to purchase more Jet.
He is the main object of the Dependency quest, in which his sister Tina asks the Sole Survivor to cure Bobby's Jet addiction. This quest can be completed by forcing Bobby to quit, or by passing a medium-difficulty speech check.