Doctor Barrows run Underworld's Chop Shop and has a pretty sick sense of humor. He hangs around the Chop Shop most of the time, often looking in on Reilly, the human female he's treating. At night, he leaves to eat dinner at Carol's Place for a few hours, and then returns to the clinic. He sleeps for a couple of hours on site. Doctor Barrows is also mayor of Underworld, although, because of the small nature of the town, his civic duties take a backseat.
He claims to be the foremost authority on the ghoul condition and he has managed to contain a pair of live glowing ones (named Meat and Ethyl) in an (inaccessible) observation cell. His business is mainly centered around the medical treatment of Underworld, but he and his assistant, Nurse Graves, are busily (but discreetly) studying a way to slow the advancement of the ghoul condition, and maybe someday reverse it. He is eager to get his hands on live samples from un-ghoulified humans.
Reilly's Rangers: He can start the quest, and also wake Reilly up. If Barrows is killed by the player, it is not necessary to wake Reilly up. If the player goes to the Statesman Hotel and helps the Rangers, Reilly will automatically appear in the Ranger Compound.
Barrows remains in the game files of Fallout: New Vegas, and he can still cure addictions and heal you. However, the quest option that he will wake Reilly wasn't there since the quest and Reilly are not in the game files.