I'm not sure a 15 year old girl who was obviously very lost at the time and sought to find a home in a dictatorship should be labelled as the protagonist.
Lots of children/teenagers are "lost" at that age, but they don't go around murdering people. Those who do are treated as criminals and threats to society.
You know why? Because at that age they have enough life experience to know that certain things are so deeply offensive to basic human decency that you simply do not do them. Like murder. Like beheading people of a different faith or culture.
She didn't do drugs, crash her bike, or stay out late. She didn't get mixed up with that boy down the road her parents don't approve of.
She went and lived with Islamic State.
As I said, what she did is so deeply offensive to basic human decency that we must treat her as a criminal; a murderer; a sociopath; a danger to society and a danger to life.