She has a strong desire to do what is best for her family:
In the book, family comes first for Marina. On page 1 Marina says, "We had to build a new life in this strange that offered us refuge when we had no where to go. I had to concentrate all my energy on survival. I had to do this for my husband and son." This quotation from marina clearly states that she was willing to do anything for her husband and son in order for them to have the best life that they could, even if it meant moving to a country that they knew nothing about and had no plans for the future. This did not matter for Marina because she didn't care where they went, they just needed to get out of Iran.
She is a very loyal friend:
Not only does Marina value her family, but she values her friendships as well. After Marina was arrested and taken to the prison in Tehran, the guards would start to question some of the prisoners. When it was Marina's turn to be questioned, the guard asked her about her friends at school and what some of their names were. Despite knowing that the guards would punish her if she gave them a hard time she told them that she would not give the names of her peers. "I won't give you any names. If I give you names, you'll arrest them. I don't want that to happen." (page 15) This accurately demonstrates how loyal and brave she is because she was willing to sacrifice being punished in order to keep her friends safe.
Here is an interesting video of Marina Nemat being interviewed by George Stroumboulopoulos on The Hour.