How does each of the characters experience the feeling of fear in Refugee by Alan Gratz?

The story contains three individual stories: those of Josef, Isabel, and Mahmoud. These children’s experiences occur in different places and times. One common thread is the threat of political violence in each setting, which is having a direct effect on the each child and their family. There is a considerable element of danger, but as their families flee, there is hope of a brighter future.
Fear is a common element in the three children’s lives. Although they are all traveling with their families, their family members are also afraid or traumatized. The protection that parents usually afford is not always extended to these children.
Josef and his family are fleeing Nazi Germany in the 1930s. The fear of looming war for them, as Jews, spurs their departure. For Josef, traveling across the Atlantic becomes a fearful time as well. His father, gripped with fear that they are actually headed to a concentration camp, hides in their cabin.
Isabel’s story begins in Cuba in the 1990s. The family’s general fear of political repression is focused on her father, who is in danger of being imprisoned. They set out on a small boat, with the constant fear of capsizing and sharks. There is also a fear of an anticipated problem: that they will be denied entry into the United States.
Mahmoud, of Syria, is twelve years old in 2015, as his tale commences. He is old enough to feel protective for his younger brother, so one fear he has is that he will not succeed in shielding him. Their travels to Turkey and to Europe on a small boat are filled with terrifying episodes. Unscrupulous “helpers” instead thwart their plans. As for Isabel, being crowded into a tiny boat is a harrowing journey.
In different ways, each of the characters and many of their family members are united through experiencing fear, but the protagonists find ways to overcome the emotion.
https://www.alangratz.com/writing/refugee/