The Kill Order Themes
The main theme of "The Kill Order" is survival. The theme is clear in the motivations of Mark and his friends. They have somehow survived the solar flares that killed millions. Now they are restarting their lives, trying to survive in a world where nature has been completely decimated. It is a difficult situation, but they are doing the best they can.
The theme of survival becomes a motivation to these characters. When Mark's settlement is attacked by people clad in green, they become ill and find themselves fighting for life in a very literal way. The virus mutates, changing from person to person and having very different results in each patient. This frightens the survivors and finds them fighting to find a cure or at least answers.
As Mark fights to find answers, he learns how the virus came to be inflicted...