Martella originally auditioned for the role five months before his initial pickup, but was left without feedback for the time. When Dan Povenmire was given a tape of Martella in "Everybody Hates Chris," he called him to do Phineas for the pilot. He designed a different voice than his own which he describes as "wacky [and] crazy." The creators were afraid of him losing it when his voice changed, though he was still able to retain it for the most part even afterward, though the tone is now slightly different than the original sound. While in recording sessions, Martella has a large amount of enthusiasm and describes it as humorous to watch him while doing a take. In interviews Martella has said that he enjoys working on the series and voicing Phineas, and appreciates the opportunity to work alongside guest stars, especially Malcolm McDowell. Martella once wrote as an article for "Popstar! Magazine" his thoughts on the role and of the show itself: "Phineas and Ferb" makes liberal use of running gags, and Phineas has several recurrent lines that are featured in most episodes. When he comes up with an idea of what adventure he and his brother are going to have that day, he says "Ferb, I know what we're gonna do today!" During the course of an adventure, Phineas is generally asked by a disbelieving adult if he is not "a little young to be..." part of whatever occupation he is currently carrying out. For example, while constructing a shrine to his sister on the face of Mount Rushmore, a park ranger asks him "Aren't you boys a little young to be restoring a national monument?" Phineas generally answers "Yes, yes I am," though on a few occasions has responded "No" or "Well, I don't think so." In every episode, Phineas and Ferb's pet platypus, Perry, disappears to carry out his job as a secret agent. The kids almost always notice this, asking "Hey, where's Perry?" Then, when Perry comes home, they say, "Oh, there you are, Perry!" Discussing Perry, creator Povenmire cited the example of his own pet cat, Sprocket, which he claimed led a "secret life" with his neighbors in order to get extra food. Phineas is portrayed as being a highly intelligent, imaginative, optimistic, and adventurous boy. The Disney Channel promos for "Phineas and Ferb" describe him as someone who "thinks big", refusing to let any day be ordinary.