I think Chapter 17 confirms readers’ interpretations of Atticus, Bob Ewell and Heck Tate. Heck comes across as simple and honest. Atticus remains calm and logical and this is illustrated in his questioning of Tate and Ewell. Bob Ewell is a contemptuous, angry man. He thinks he can match wits with Atticus, but his ignorance is revealed when Scout notes that Atticus is showing that it is more likely that Mr. Ewell could have beaten up Mayella. Mr. Ewell also reveals his ignorance when he says that he is not ambidextrous and that he can use either hand as well as the other.
The only character that I might say changes is Scout and I only say that because the entire novel is from her perspective as she evolves throughout these situations. Jem tells Reverend Sykes that Scout doesn’t understand so that he agrees to let her stay. In fact, she does understand what’s going on.