How does Jem react when Atticus tells him to go home? How does this characterize Jem?

Jem refuses to leave his dad's side. Really Jem shows the steadfast courage that his dad shows,

Jem shook his head. As Atticus's fists went to his hips, so did Jem's, and as they faced each other I could see little resemblance between them: Jem's soft brown hair and eyes, his oval face and snug-fitting ears were our mother's, contrasting oddly with Atticus's graying black hair and square-cut features, but they were somehow alike. Mutual defiance made them alike.