Yep, you know the drill. Fanart50 Challenge #37: Thief
Kind of based on my story "Keep Your Enemies Closer", but I decided to make the other agent a human. Bonus points if you can guess which agent it is. Hint: He's in the show and he has a name.
EDIT: Yes, Monogram now has a mustache. My bad for forgetting it the first time Phineas and Ferb ©