In his book, Story, Robert McKee writes that multidimensional conflict arises as the protagonist moves from the inciting incident towards the turning point at the end of act one.
The conflict persists in act II, but the second act, being the longest stretch of the story, needs to add complexity to the conflict in order to sustain and escalate it.
But how is complexity added, and what is it, exactly?
Complexity, according to McKee, springs from the interaction between three layers of conflict: inner, personal, and extra-personal.
“Complexity arises when a character undergoes multidimensional conflict.”
In Kramer Vs. Kramer, for example, Ted Kramer, whose wife has left him and his son, is torn by inner conflict. He loves his son, but is afraid that he is in over his head. Can he bring up the child on his own?
Additionally, he experiences, at least initially, a personal conflict with the boy who is terrified that he will starve without his mother to feed him. Ted has a hard time pacifying the hysterical child. The personal conflict will increase later when Joanna, Ted’s deserting wife, reappears on the scene and demands her son back.
Ted, also experiences extra-personal conflict—conflict with his enviroment. The kitchen, for example, is presented as a dangerous, alien place for the inexperienced father. Ted does his best to feign confidence. Things, however, degenerate rapidly as is he tries to fry eggs for his son.
As the ill-equipped Kramer struggles with these internal and external forces that threaten to defeat him, comedy turns into pathos.
In The Nostalgia of Time Travel, a middle-aged theoretical physicist, too, is beset by complex internal and external conflicts. Years of deep-seated guilt, an almost intractable mathematical problem, and an approaching category-five cyclone threaten his life. As the cyclone rages around him he tries to resolve se complex conflicts in order to survive.
Narrative complexity arises when a character experiences inner, personal, and extra-personal strife, resulting in multidimensional conflict.