|Affiliation:||Counter Terrorist Unit|
|Profession:||Field agent, CTU Los Angeles|
|Played by:||Brian Durkin|
|First episode:||"Day 2: 8:00pm-9:00pm"|
|Last episode:||"Day 3: 5:00am-6:00am"|
Brian was present at the field agents' meeting at Norton Airfield during the terrorist crisis involving Second Wave. He listened as Jack Bauer assigned tasks and explained that a nuclear bomb was located somewhere nearby, and to use extra caution as paramilitary Coral Snake operatives would be a threat to them. ("Day 2: 8:00pm-9:00pm")
When the bomb was found, Brian plotted flight paths to both the desert and the Pacific Ocean to dispose of the bomb on Jack's order. ("10:00pm-11:00pm")
As Jack left CTU Los Angeles with Kate Warner without permission, Brian quickly slipped him the keys to and location of a vehicle. Brian slipped away, and immediately afterward, Jack had to knock down Tony Almeida who tried to stop him. ("11:00pm-12:00am")
Pierson and fellow field agent Jimmy Bronson were present in Tony Almeida's briefing on Kyle Singer in the conference area. Both agents later accompanied Almeida to the shopping mall where Singer was located. After the chief security guard told Tony where Singer was, Tony instructed Pierson to go to the security office to run point and observe what happens. ("Day 3: 3:00pm-4:00pm")
About twelve hours later, Peterson and Pierson accompanied Michelle Dessler to the Chandler Plaza Hotel when there was an outbreak of the Cordilla virus. Like the other agents, he was not wearing protective breathing gear and was potentially exposed to the airborne weapon. ("3:00am-4:00am")
Background information and notes
- Though the character's first name was spoken by Jack during Season 2, Brian Durkin was only credited for playing a "CTU Officer".
- As was the case with many of the background CTU first-responders at the Chandler Plaza Hotel (including Ed Miller, Peterson, and the Division agent), it was not specified if Pierson survived the Cordilla virus attack there. However, the actor Brian Durkin did confirm on his Twitter account that his character was indicated as being killed off by the virus.