Over time, everything in the world becomes childproof after fear of repeats of Phineas and Ferb's dangerous activities and Doofenshmirtz gains the upper hand, effectively becoming emperor of the world.
Everything in the world becomes childproof after fear of repeats of Phineas and Ferb's dangerous activities. This is over time. This is effectively. Doofenshmirtz gains the upper hand. This is over time. This is effectively. This upper hand is becoming emperor of the world.