Dave is competitive, clever, and outgoing. 

In No Talking by Andrew Clements, Dave reads a book that includes information about Mahatma Gandhi's weekly period of silence. He is fascinated by the idea that Gandhi spent a whole day quiet every week to "bring order to his mind," he and decides to try to do so.

When Dave has to give a speech in front of the class—and doesn't want to break his vow of silence—he displays his clever mind by coughing so violently that he is excused from the oral report. It works, though it alerts a girl in his class to what he is attempting to do.

When Lynsey annoys Dave in the lunchroom, the two of them decide to make the silent period a contest between the fifth-grade boys and girls, showing Dave's competitive spirit. He's willing to go to great lengths to stay quiet and help the boys win. Competitive people are usually more willing to go to extremes to come out the winner—and Dave shows this throughout the novel.

Dave is also outgoing. When his teacher challenges his silence and yells at him in front of everyone, he ultimately yells back at her. He insists that he—and they all—have the "right to remain silent." Before his vow of silence, Dave was also known for talking a lot. He has many friends who are willing to follow his example in the competition, staying quiet even when it confuses or alarms those around them.

This novel is about a typical class of easily excited and slightly out of control 5th graders, so much so, that the teachers have nicknamed them "The Unshushables." Dave Packer, the protagonist, could first be considered a leader in his class.  As an "Unshushable," Dave is a leader by example.  He is a charismatic student who likes to talk nonstop.  But unlike a stereotypical chatterbox, Dave is also a thinker.  After reading about Mahatma Ghandi, and his remaining silent for long stretches in order to clear his mind, Dave wants to give the idea a try.

He sets out to accomplish this on his own at first, showing that he is not merely swayed by peer pressure, but rather is someone who is independent and somewhat daring to go against what everyone else is doing.  He also displays self-control and perseverence in this quest.  His idea eventually leads to a boys vs. girls no-talking challenge and Dave (along with the rest of the class) proves to be somewhat immature compared to typical 5th graders as the class indulges in a very heated gender rivalry.  By the end of the story, Dave and the rest of the class learn valuable lessons as a result of the experience which shows that Dave is a dynamic character who is changed for the better.