How does the author show the nobility of Luke's character?

When Katie returns to her narration about the past, she shares with the reader the story of how Luke struggled to find work because he felt it was important to be with the girls during the day. This shows the reader how noble and strong in character Luke was despite his previous typical teenage behavior. The reader worries that Luke does not fully understand what he has in store for his future but sees that he is fighting hard to be a good guardian to his younger sisters.