This one part of the movie really made me laugh, so I thought "Hey! What if Ferb really did lead a secret double life?"

Which led to this. Enjoy!

Double Lives

"Is anyone else here leading a bizarre second life?" Phineas glared at Perry, not willing to give into this whole 'I'm actually a secret agent' thing easily.

Ferb said nothing, but decided that if there was going to be a time to fess up, this would be it. He raised his hand, sure to keep his expression neutral.

"Put your hand down, Ferb."

Wonderful. So, Phineas wasn't going to believe him. Oh, well, it was hard enough trying to grasp that the pet you had treasured for ages was actually a secret agent with his own theme music, logo, and everything without simultaneously trying to grapple with the fact that your step brother was actually a member of a top secret interdimensional crime fighting group.

He lowered his hand.

There would be a better time to explain.

x-x-x

"…you could have been cleaning your own litter box this whole time! Oh, we are so not through with this."

Or, then again, he might just keep it secret forever…