Perry was adopted 5 years ago by the Flynn-Fletcher family (after Bucky got ill and left) from an animal shelter run by the O.W.C.A. The boys chose him because of his wall-eyed gaze that made it appear as though he was looking at both Phineas and Ferb at the same time. When they adopted the platypus, he was given the name "Bartholomew" before he was renamed "Perry" (Phineas and Ferb The Movie: Across the 2nd Dimension). According to Phineas, he has always enjoyed listening to music ("Oh, There You Are, Perry").
While undercover, Perry can normally be found with his owners, Ferb and Phineas. As their pet, he lives up to the expectations for a platypus and "doesn't do much." He is also serious while on duty as an agent, even in front of Major Monogram when he does anything silly ("Jerk De Soleil", "Boyfriend From 27,000 B.C.", "Traffic Cam Caper", "Skiddley Whiffers"). Perry appears to be selfless and devoid of vanity. In "The Best Lazy Day Ever", it is only after he turns everything else affected by the Ugly-inator back to normal that he reverts himself to his normal state. He deeply cares about the Flynn-Fletcher family and is afraid to lose them. He will take immediate action whenever they are threatened ("Journey to the Center of Candace", "Phineas and Ferb Get Busted!", "Oh, There You Are, Perry", Phineas and Ferb The Movie: Across the 2nd Dimension, "Where's Perry?", "Where's Perry? (Part Two)"). He is nice to not only his allies, but to his nemesis Dr. Doofenshmirtz as well, though only on some occasions ("Oil on Candace", "Thaddeus and Thor", "Brain Drain", "Skiddley Whiffers", "When Worlds Collide", "Road to Danville").
Perry has a lair under the Flynn-Fletcher’s house that can be entered through various passages. Entrances inclue Chimney-Vator (in which he encounters Santa), one in the side of the tree, another in the side of the house, one in the middle of the backyard, and various others scattered throughout the property and even other parts of the city.
His nemesis is Dr. Heinz Doofenshmirtz. Perry's mission is almost always foiling the doctor’s plans, which he successfully accomplishes almost every time even with minimal details about the plans. Typically, during these missions, his battle with Dr. Doofenshmirtz unintentionally cleans up whatever Phineas and Ferb have been working on that day. For one mission (and only one mission) his nemesis was The Regurgitator, who is now in prison ("Oh, There You Are, Perry").
Perry receives wages from the O.W.C.A. for his work. He is seen paying for Doofenshmirtz’s door (“Lights, Candace, Action!”) and cans of oil (“Traffic Cam Caper”). Major Monogram has mentioned a huge bonus check (“The Lake Nose Monster”). He gives a girl $20 for her skateboard after Dr. Heinz Doofenshmirtz stole a boy’s bike (“Leave the Busting to Us!”). He pays 25 cents for an arcade machine ("Ain't No Kiddie Ride").
Role in the series
Because his arch-nemesis is a member of Team Nefarious, he and the rest of the OWCA are members of the Anti-Team Nefarious Freedom Fighters. Though the Lodgers and other hero teams know both him and his owners (Especially since the events of Spyro and Friends Meet The Little Mermaid), they have made an oath to help protect his cover however they can.