What three things does Bob Ewell do in chapter 27 of To Kill a Mockingbird that alarm Aunt Alexandra?
Bob Ewell is enraged against those who didn't take his word as a white man over Tom Robinson's. Winning the trial and Tom's death in prison are not enough to satisfy Bob Ewell's bruised pride. As a result, Bob Ewell blames Judge Taylor and Atticus Finch for his troubles. He also antagonizes Tom's widow in the process. A foreshadowing of Bob Ewell's disgruntled attitude appears in chapter 23 when he spits in Atticus's face and threatens to kill him. After that happens, Atticus tells his family not to worry if Bob Ewell will ever follow through with his threats. Aunt Alexandra says,
I wouldn't be so sure of that, Atticus... His kind'd do anything to pay off a grudge. You know how those people are (218).
By chapter 27, Bob Ewell is still fixated on the trial. Scout says Ewell "found himself as forgotten as Tom Robinson" (248). So Ewell tells Ruth Jones at the welfare office that Atticus is to blame for "getting" his job. This incident concerned Ruth enough for her to tell Atticus about it, but he isn't very concerned. That is the first "thing" Ewell did that seemed out of the ordinary. It is also concerning because the spitting incident apparently wasn't enough for Ewell to forget about Atticus.
Next, Bob Ewell creeps into Judge Taylor's yard and slices the back door's screen on a Sunday night when the judge was home alone. Judge Taylor caught a shadow running out of his backyard, so he continued the rest of the night sitting with his shotgun as a precaution. To make matters worse for Tom's widow, Ewell's children "chunked" at her when she walked by their house to go to work for Link Deas. Ewell would then yell obscenities at her until Deas told him to stop. Ewell doesn't stop until Deas threatens to press charges on Ewell for continuing to follow Helen to work. All of these actions point to the fact that Ewell was not one to let go of a grudge, just as Aunt Alexandra said. Alexandra voices her opinion again in chapter 27 with the following:
I don't like it, Atticus. I don't like it at all... That man seems to have a permanent running grudge against everybody connected with that case. I know how that kind are about paying off grudges, but I don't understand why he should harbor one—he had his way in court, didn't he? (250).
Still, Atticus isn't very concerned. He can't do anything about Ewell anyway until Ewell actually commits a crime. Ewell dies during his next attempt to seek revenge, but it proves Aunt Alexandra was right to be concerned about his behavior.
Bob Ewell is fairly active following the trial, and in all the wrong ways.
First, he gets a job at the WPA and then gets fired for laziness. He then blames Atticus for having something to do with him losing his job.
Next, someone is prowling around outside of Judge Taylor's house. Although it is not directly stated, we get the impression it was Bob Ewell.
Finally, Link Deas hires Tom Robinson's widow, Helen. She has to walk past the Ewell house on her way to work, though, and when she does the entire Ewell family "chunks" at her, meaning they hurl insults at her as she passes. She starts taking another route to work, but it takes her a mile out of her way. When Deas hears about this he threatens Bob Ewell and his family and tells them to stop yelling at her. Then Helen starts walking past the Ewell house again only to have Bob follow her all the way to work singing nasty names about her.
All of this leads Aunt Alexandra to remark,
"I don't like it, Atticus. I don't like it at all. That man seems to have a permanent running grudge against everybody connected with that case. I know how that kind are about paying off grudges, but I don't understand why he should harbor one - he had his way in court, didn't he?" (Ch. 27).
Judge Taylor hears someone (Bob) prowling around his house. He also loses his job with the WPA a few days after getting it. Finally, Bob follows Helen Robinson around as she goes to work, whispering obscenities after her.