There will come a time in your story where your characters don't feel up to the task ahead. Though there are a myriad of reason why this could be, the most common is inferiority. They do not feel good enough, strong enough or powerful enough to take on that final task. Inferiority can also be laced into a character from the beginning. Perhaps they've been bullied for a long time, or perhaps they've turned to bullying as an outlet for their own feelings of inferiority. Whatever it is, you can use it in your story to create depth in your characters.