Denise Petski Senior Managing EditorEXCLUSIVE: We’ll be seeing more of FBI Agent Devin Rountree on NCIS: Los Angeles. Caleb Castille, who recurred as the character last season, has been promoted to series regular for Season 12 of the CBS series.After Castille’s Devin Rountree appears on the radar of NCIS’ Office of Special Operations, Agents G.