Phineas comes from a blended family . The creators chose this arrangement because they considered it underused in children's programming as well as from Marsh's experiences in one.  As a character, Phineas has received a positive critical response, with one reviewer describing him and his brother as a "comical pairing."  Phineas appears in Phineas and Ferb merchandise, including plush toys ,  t-shirts ,  and a video game . 
Creators Dan Povenmire and Jeff "Swampy" Marsh had previously worked together on Fox's The Simpsons and Nickelodeon 's Rocko's Modern Life . The creators also voice two of the main B-plot characters: Major Monogram and Dr. Doofenshmirtz. Phineas and Ferb was conceived after Povenmire sketched a triangular boy – the prototype for Phineas – in a restaurant. Povenmire and Marsh developed the series concept together and pitched it to networks for 16 years before securing a run on Disney Channel .