Agent O'Brien was a S.H.I.E.L.D. agent active in 2008. He was part of the team led by Agent Hart that went to Bahrain to apprehend the potential gifted person Eva Belyakov. When Agent Phil Coulson failed to get her to turn herself over to them peacefully, Agent O'Brien and the other members of the S.H.I.E.L.D. team tried to apprehend her by force. However, O'Brien and the rest of the agents all fell under the control of Eva's daughter Katya, who unknown to them had the power to make anyone she touched her slave. Agent Melinda May freed O'Brien and the other agents from Katya's control when she killed her. What happened to him between the events in Bahrain and the fall of S.H.I.E.L.D. are unknown, but Agent O'Brien became a member of the reformed S.H.I.E.L.D. with Phil Coulson as its director. O'Brien took part in a failed mission led by Melinda May to kill the ancient Inhuman known as "Hive."