Dill is clearly the most innocent and naive character in To Kill a Mockingbird; however, that does not mean he isn't aware of some important aspects of human nature. When we meet him, he's still wearing short pants, which is why the Finch children assume he's much younger than he actually is. Charles Baker Harris is known as Dill, and because he has an active imagination, he constantly makes up stories about himself and his family. These tall tales are another indicator that Dill is rather immature. He wants to play games which focus on the outrageous aspects of the Boo Radley story, as any child would. At the trial, Jem is both incensed and wounded by the eventual outcome. Jean Louise is relatively unmoved by it all. Dill, though, has to leave the courtroom because he has burst into tears after Mr. Gilmer cross-examined Tom Robinson. He has trouble articulating what has prompted his outburst, other than to say,
"It ain't right, somehow it ain't right to do 'em that way. Hasn't anybody got any business talkin' like that--it just makes me sick."
And Dill is right. It's true that Mr. Gilmer was just doing his job, but Dill intuitively recognized the injustice of the entire proceeding. And that's the point, it seems to me, if even the most naive and innocent child can understand the inherent injustice of this trial, why can't the jurors? Dill's innocent presence in the novel helps underscore the obvious flaws in this town and its inhabitants. His tears represent a loss of innocence due to the deep-seated prejudices and biases of these people at this time in this place which cost an innocent man his life. He, apparently, understands what most adults who are supposedly much smarter and experienced do not--that a human being has worth and dignity no matter what color his skin, and he should be treated as such.