Yes, his threat was real and he lived up to it when he tried to stab Jem and Scout and Atticus said, "I knew he would get me back but I never imagined he would do it through my children."
Aunt Alexandra is suggesting that Bob Ewell might try to harm Atticus in a secretive or sneaky way as revenge for defending Tom Robinson in court. She is concerned about the potential danger that Ewell poses to her family.
Jem does not want Scout to tell Atticus about Bob Ewell's comment because he fears that it might upset Atticus and cause trouble. However, it is not wise to keep such important information from Atticus, as he is their father and can handle the situation appropriately. It is important to communicate openly and honestly with trusted adults when dealing with serious matters.
Atticus underestimates Bob Ewell's capacity for violence due to his belief in the goodness of people and his tendency to see the best in everyone. He also prioritizes empathy and understanding over suspicion and fear, which blinds him to the true intentions of someone like Bob Ewell. Additionally, Atticus may have been distracted by the trial and his own sense of moral duty, causing him to overlook the warning signs.
In "To Kill a Mockingbird," Atticus Finch's defense of Tom Robinson to the jury might be considered a counterclaim to the prosecution's argument that Tom is guilty of assaulting Mayella Ewell. Atticus argues that the evidence points to Tom's innocence and that racial prejudice is clouding the judgment of the jury.
Atticus is teaching Jem the same lesson he taught Scout- You never really understand a person until you climb in to his shoes and walk around in them. These are the ugly facts of life that Atticus talks about a couple of pages on in the book ( when it's a white man's word against a black man's, the white man always wins. They're ugly, but those are the facts of life.) Atticus is putting his own lessons in to practice, so effectively this is repetition from very early on in the book (i'm not too sure about that) about standing in people's shoes. This builds tension as well because of the words associated with violence (destroyed, threatening, beating)- it makes us fear for Atticus's safety.
Atticus found out about the children's game involving Boo Radley when Heck Tate mentioned it during Tom Robinson's trial. Tate revealed that he had asked Atticus not to tell the children about Mr. Radley's courage in saving them from Bob Ewell, as it might prompt them to reenact the story. This indicated to Atticus that the children had indeed been playing a game about Boo Radley.
Mayella was afraid of Atticus in the courtroom because he was treating her with respect and she had never been treated like that before. She was also afraid of Atticus because he might ask her questions and she might give him answers that could lead him to the truth and then her father would do horrible things to her.
Angry is a person who is not happy. A person might get angry if he/she is provoked.
Heck Tate is the sheriff of Maycomb county and warns Atticus about the mob that might try to take Tom Robinson from the jail one night, he also gets led off on a wild goose chase so that the mob can get to Tom Robinson. Heck Tate is as tall as Atticus but is thinner, he has a long nose and wears boots with shiny metal eye-holes, he also wears boot pants and a lumber jacket. Heck Tate's belt has a row of bullets sticking in it. He carries around a heavy rifle which Atticus uses to shoot a "mad" dog. Heck Tate beliefs that Tom is innocent but knows that he must arrest him because Bob Ewell says he in guilty of raping Mayella Ewell "Bob Ewell's daughter". At the end of the book Heck Tate says that he beliefs that Bob Ewell got what he deserved.
He was a country folk and Atticus had worked with them a lot and knew he was comfy just leaning against the wall. that stranger is no stranger. he is Boo Radley and he had saved jem and scount from Bob Ewell.
Heck says "Didn't you know your daddy's-" (page 128) Then he is cut off by Atticus saying "Hush, Heck, let's go back to town." What Atticus is trying to avoid here is another lie about him that he is tired of people saying.
It depends from person to person. One might be angry regularly while other might not get angry at all.