Steven's second in command of security
Brian was a young Visitor officer who became a leader of the Friends of the Visitors youth corps soon after the First Invasion. As Daniel Bernstein continued to prove his devotion and loyalty, he became Brian's second-in-command as well as his only known human friend.
Brian befriended Robin Maxwell, and when she became a prisoner on the Los Angeles mothership, Diana enlisted him to conduct an experiment in inter-species reproduction. (V: The Original Miniseries)
Brian is about to experiment with Robin
By the next year, he had become one of Diana's numerous lovers.
In the run-up to John's announcement of the discovery of a cure for cancer at the Los Angeles medical center, he witnessed his intoxicated subordinate Gary eating a mouse in public. Chastising Gary, he reminded him of their standing orders never to eat in the company of humans. A homeless man saw Gary taking the mouse from a dumpster and ingest it. Brian immediately dealt with him, though it is unclear if he was killed at that time or taken to a food processing facility.
After Diana and Steven witnessed Dr. Corley Walker accuse the Visitors' official spokeswoman Kristine Walsh of being a propagandist for fascists, they ordered Brian and his shocktroops to bring him to the LA mothership for conversion.
In order to curry favour with Pamela, Steven ordered Brian to locate Mike Donovan's son Sean Donovan so that they could plant a spy in the Resistance. Brian soon found Sean in one of the LA mothership's food storage chambers and turned him over to Diana, who converted him in short order.
Shortly afterwards, Daniel was set up by the Resistance to be seen by the Visitors as Brian's betrayer when Brian was captured and used as a test subject for the Red Dust. Daniel was tortured by the Visitors before being sent to a food processing facility on Steven's orders.
Brian dies from the Red Dust.
While Brian remained imprisoned in a Resistance holding cell, he was visited by Robin and their daughter, Elizabeth. As Brian tried to manipulate Robin into setting him free by appealing to her "love" for him, Elizabeth impulsively flung a sample of Red Dust into the cell, causing Brian to sicken and die from the dust. He was the first Visitor to suffer this fate.
Robin was later haunted by the expression of agony on Brian's face as he died. (V: The Final Battle)
Behind the Scenes
Brian's closest analogue in the re-imagined series is the similarly-named Ryan Nichols, a Visitor sleeper agent turned Fifth Columnist, who is also the father of a human-V hybrid. Initially, Lisa seemed a female analogue of Brian, as she was an officer in the Peace Ambassadors program (the new version of the Friends of the Visitors) and entered into a relationship with a human. Lisa, however, is much higher-ranking than Brian was, and her feelings are genuine, whereas Brian's were faked.