Initially opposed to the Duck Avenger, she later begins trusting him and become friends. However, it isn't clear if that friendship is really selfless, as Mary Ann doesn't doubt about using the Avenger several times to carry on dangerous missions, or using him to get Uno's help. The sense of being manipulated eventually has the Duck Avenger breaking any link with the PBI.
She makes her first appearance in PKNA 4: Earthquake. She opposes the Duck Avenger and tries to arrest him several times as the hero is investigating some top secret experiments on the west coast. The agent fights the masked duck until she discovers professor Morgan Fairfax's project Pangea, a mad visionary dream to destroy the entire west coast.
Agent Flagstarr re-appears in the 1997 special "Missing" investigating the Duck Avenger's disappearance. Later in PKNA #17, the newly-promoted Lieutenant Flagstarr crosses paths with the superhero as they both look for Xadhoom, who is wandering Duckburg out of control.
In PKNA #21, Mary Ann asks for the help of the Duck Avenger and Uno because Fairfax has escaped from prison and allied with the Republic of Belgravia to complete project Pangea.