During the Phineas and Ferb series, Perry is seen as a domesticated pet to the Flynn-Fletcher family, although he also leads a secret double life as an agent for an all-animal espionage organization referred to as the O.W.C.A (Organization Without a Cool Acronym). He often makes use of everyday objects as secret entrances to his underground lair, such as the side of the Flynn-Fletcher house or a tree in the backyard. He also uses his various technology and inventions created by the O.W.C.A to protect the Flynn-Fletchers and their friends from the Norm-Bots, and also to help them out of trouble, such as when he helped guide Phineas, Isabella, Heinz, and Candace back home after they were chased by the Platyborg and 2nd Dimension Doof.
Despite his appearance as a mindless, domesticated pet, Perry is actually quite intelligent and well-adjusted. He is able to keep up with the Phineas and Ferb gang in their various adventures, including improvising combat moves and escaping from a variety of obstacles. He is very loyal to his owners and is always willing to put their needs ahead of his own, as demonstrated when he sacrificed himself while attempting to protect them from the Platyborg. He also puts the safety of his family above his own in Across the 2nd Dimension, when he blows his cover while helping Phineas and Ferb battle the Norm-Bots, even though this causes him to be left behind.
He is an expert martial artist and can perform a variety of implausible judo fighting maneuvers. He is also capable of a number of high-speed acrobatics, such as jumping up onto the top of the Platypusmobile and throwing a bomb down on Doofenshmirtz in his lair.
When not on duty, Perry likes to hang out at the ice cream shop with his owners and their neighbors, especially Isabella and Stacy. He also enjoys playing video games and watching television, and is a huge fan of the animated sitcom, The Simpsons. He is an avid fan of the show’s theme song and can be heard reciting its lyrics throughout the episode “Candace Disconnected”.
Perry is very close to Major Monogram, as he often acts as her guardian when she is away from the laboratory. He and Monogram are also a team, and often work together to stop Doofenshmirtz’s evil plans.
Despite their arch-nemesis status, Doofenshmirtz and Perry are sometimes cordial towards each other. Doofenshmirtz frequently tries to impress Perry by showing him his latest gadget, but Perry is quick to point out that the device is often a failure in actual practice.
Several items of Phineas and Ferb merchandise feature Perry, including the 20-inch plush version of the character which features a button that emits his signature chattering noise. He is also featured on the front and back covers of the series’ official novelizations, and has appeared on t-shirts sold by both Disney and Zazzle. In addition, Perry appears in the Phineas and Ferb the Movie: Candace Against the Universe film.