The author helps the reader understand how the lives of Young Hoon and Young Jun change over the course of the text by providing specific details about their journey from North Korea to South Korea and their new life in Seoul. The author states that the brothers and their family members risked their lives to reach South Korea because staying in North Korea meant facing starvation. This suggests that their lives in North Korea were very difficult and filled with hunger. However, in South Korea, the brothers are described as happy and living in an apartment where they eat well. The author also mentions that they now enjoy activities like watching movies and playing video games, which they couldn't do in North Korea. This highlights the significant improvements in their quality of life after moving to South Korea. Additionally, the brothers share their hopes and dreams for the future, including Young Hoon wanting to be a pilot and Young Jun wanting to help people. This indicates that they now have aspirations and opportunities that were not available to them in North Korea. Overall, the author provides these details and examples to illustrate the positive changes that have occurred in Young Hoon and Young Jun's lives since leaving North Korea and starting anew in South Korea.