PHXenon Caelum
Established
Phineas and Ferb are simply a figment of Candace’s imagination. After not being able to handle Phineas’s tragic childhood death, and Ferb having a disability that restrains him from talking or moving much, Candace creates a world in her head where phineas and Ferb play together and create incredible things. This is why her mom is never able to see these things. Not because it is coincidence, but because they are simply not there and never existed in the first place. Dr. Doofenshmirtz is just Candace’s psychologist, whom she sees twice a week in order to try and get her back to normal. The last Phineas and Ferb episode includes the two brothers headed off to college, representing Candace’s acceptance of her younger brothers death, and moving forward.