In chapter 9, Uncle Jack comes to celebrate Christmas with the family. Most of his time is spent worrrying about Scout's new habit of, "...cussng fluently for over a week."
Jack and Atticus don't really get to talk about the case much until after Christmas dinner at the Landing with Alexandra, her tacit husband Uncle Jimmy and her grandson Francais. Francais provokes Scout by calling Atticus a "nigger lover." Even though she's not sure what it means, she knows it's bad, so she hits Francais so hard in his teeth that she hurts her hand and attempts to use the other one, but Uncle Jack pins her arms down and tells her to stay still. She runs and he tackles her. Scout tells him how much she hates him and wishes he would die.
Once they arrive back home, Uncle Jack goes to see Scout and she explains how he never gave her a chance to explain her side of the story--like Atticus would. Once he hears what Francias said he wanted to drive out to the Landing. Scout begs Uncle Jack not to tell Attius because she doesn't want to upset Atticus. They make up and Jack goes out to the lving room where he and Atticus have their first conversation about the case.
The first thing Uncle Jack says is, "Atticus, how bad is this going to be?"
Atticus replies, "It couldn't be worse." He says this because it's a while woman's word against a black man's. It's important to note that Uncle Jack has lived in Boston for many years where racial tensions were no where near as hostile as Maycomb.
Atticus remarks that, "Before I'm through, I intend to jar the jury a bit-". He also remarks that he thinks they will have a beter chance on appeal. Atticus admits to Uncle Jack that he he is still not certain about the case and he had hoped he would never be faced with one like this his entire life.
Uncle Jack understands how Atticus must be feeing; Uncle Jack is a sounding board for Atticus; he listens to Atticus and says, allusion to the Bible, specifically to Matthew 26:39. He says, "Let this cup pass from you, eh?"
Uncle Jack is the only Finch, other than the dhildren who worries only abut Atticus's feelings.
Jack Finch has had no time to discuss the Tom Robinson trial with Atticus before arriving in Maycomb for Christmas, but following his intervention between Scout and Francis, the two brothers have a bit of time to talk. Naturally, Atticus's brother sides with the family concerning the trial. Jack is familiar with the Ewells from his earlier days at Finch's Landing, since they have been the "disgrace of Maycomb for three generations." But Jack actually has little else to say about the upcoming trial. He knows that things may get hot for Atticus--"... how bad is this going to be?"--and when Atticus explains that he has been assigned to the case by Judge John Taylor, Jack responds
"Let this cup pass from you, eh?" (Chapter 9)