To see another the four perspectives necessary in every complete story, first put yourself in the shoes of the Main Character. You are right in the middle of the story’s battle. Smoke from dramatic explosions obscures the field. You are not absolutely sure which way leads to safety. Still, before there was so much turmoil, the way was clear and you are confident in your sense of direction.
Then, from out of the smoke a shadowy figure appears, solidly blocking your way. The shadowy figure is your Obstacle Character. You can’t see well enough to tell if he is friend or foe. He might be a compatriot trying to keep you from stepping into a mine field. Or, he might be the enemy luring you into a trap. What to do! Do you keep on your path and run over this person or try the other path instead? This is the dilemma that faces a Main Character.
To completely explore the issue at the heart of a story, an Obstacle Character must present an alternative approach to the Main Character. The Obstacle Character Throughline describes the advocate of this alternative path and the manner in which he impacts Main Character.
From the Dramatica Theory Book