It intensifies the conflict.
A complication adds to the problem of the story. The stories problem is the conflict. Many times there is more than one complication. When labeling a plot line for a story, the complications can be found in the rising action. This takes place between the exposition and the climax. The exposition of a story introduces the characters, setting, and conflict. The climax is the pivotal point in the conflict. The character can never return to the way things were when the story started out. Something or someone has been irrevocably changed.
