Doofenshmirtz is an interesting story of "redemption" when it comes to Disney villains, as a lot of them tend to be very serious and outright evil on every sense. They are often reflections of bad aspects of real life embodied on a character. With Doofenshmirtz, they took that concept and completely reversed it by making the villain himself be the victim of those bad aspects of life instead of him inflicting them upon others, which he then used to develop principles that go against them and be a lovable villain instead.

And the funniest part of all is that him being a villain is not even part of his character development: that just happened by chance along everything else.

She just mentioned the tri-state area at random and that was it. He did not even truly want to be a villain, he was just like "hey but that could actually work right?" and there we go.

I like how he just had one kid so he wouldn't repeat the mistake one favoring one kid over the other