Phineas Flynn and his stepbrother Ferb Fletcher keep Perry as a pet but think that he’s just a regular platypus who “doesn’t do much”. Whenever Phineas has an idea for what he and Ferb will build that day someone asks “hey, where’s Perry”. Perry is actually a spy working for OWCA (the Organization Without a Cool Acronym) while wearing a fedora and is said to be OWCA’s best secret agent. Perry’s boss Major Monogram normally sends him to fight Dr. Doofenshmirtz. In almost every episode, Perry the Platyus shows up at Doof’s headquarters, Dr. Doofenshmirtz traps Perry, Doof explains his evil plan, Perry escapes, Perry and Dr. Doofenshmirtz fight, Perry beats Doofenshmirtz and Doof yells “Curse you, Perry the Platypus.” That said, there are some exceptions to this. For example, in the Season One Episode Journey to the Center of Candace, Dr. Doofenshmirtz decides to “mix it around a little” by beginning with describing his evil plan and then trapping Perry, but as soon as Dr. Doofenshmirtz explains his plan is “to destroy anyone who can’t make up their mind” Perry immediately catches and arrests Doof after having a flashback to his owner Phineas Flynn saying he couldn’t make up his mind.