When Scout, Jem, and Dill are at the jailhouse, how does Jem react after Atticus tells him to go home and why?

Inof
, a crowd of men comes to the Maycomb jail, whereis guarding Tom Robinson
inside. They clearly plan to get Atticus out of the way and lynch Tom Robinson so that they can
carry out vigilante justice and deny Tom his right to a trial, however flawed that trial might
be. Atticus tellsto go home (and to takewith him) to protect him, but Jem stands his
ground: 

"As
Atticuss fists went to his hips, so did Jems, and as they faced each other I could see little
resemblance between them: Jems soft brown hair and eyes, his oval face and snug-fitting ears
were our mothers, contrasting oddly with Atticuss graying black hair and square-cut features,
but they were somehow alike. Mutual defiance made them alike" (page 152; page numbers vary
by edition).

Jem refuses to go home because he thinks the
men might harm Atticus in his absence. He also refuses to go home because, as this passage
implies, he is quite similar to Atticus. While Jem resembles his mother (who is deceased) in
physical traits, his character is like that of Atticus. Like Atticus, Jem has a great deal of
integrity, and once he decides something is right, he will not back down. Atticus is of course
similar in his defense of Tom Robinson. It is, in the end, Scout who gets the men to back down
when she reminds Mr. Cunningham that she is friends with his son, Walter, and she speaks about
the entailment case in which Atticus is helping Mr. Cunningham. In response, Mr. Cunningham
suddenly feels ashamed of acting as he has in front of children, and he tells the men to leave.
As Jem and Scout are heading home, Atticus ruffles Jem's hair, which is a rare sign of
affection. This gesture shows that Atticus understands that his son is a person of bravery and
integrity.