Fan Casting Dangerous Deserter in Sort by Tropes

The problem is not just their dishonorable abandonment. The real problem is their now-desperate situation. Desertion is usually punishable by death, so these people have no more incentive to refrain from other capital offenses, like murder, and every reason to engage in them if they think you'll turn them in. They also tend to be armed. They tend to steal what they need from the surrounding countryside. And they can't just settle down, lest they be caught.