Don Quixote as drawn by Picasso.
Characters are keys to the entrances and exits of your narrative. They can unlock back stories, front stories, and subplots. You first have to consider if you are writing your sentences in an Objective or Subjective point of view, Objective structure is based more on showing us what is happening as if from an outside neutral voice, one that isn’t directly related to the characters within the story. It's closer to the Diegesis in the sense of the story being told rather then actually being shown by events taking place as they unfold.
Subjective writing is based on narration or character perspective. What is happening inside the world of the story as if separate from our world or the world of the viewer. The characters should be believable, from a story-tellers point of view you are using Mimesis as drama as "an imitation of an action" as Aristotle would have it.
Two forms of Subjective narration carries our character along, the first is First Person where the story-teller uses “I” as if told by the character, from the character’s own voice. The second is Third Person (Closer to the Diegesis) where the story-teller tells the story as if telling the reader/viewer about the character but still from a Subjective point if view. Finally a Second Person Narrative which is more Objective talks directly to the reader/viewer, addressing us and communicating with us as if having a conversation from within the narrative to the outside world, thus bridging the gap.
Characters help the story or plot unfold, ideas and events are communicated or actioned by the direct relationship the characters have with that “world”. Coherence will depend on how you interact your characters with the narrative, and vice-versa.
An important relationship is that of “suspense” or tension mounts, in R. Michael Young's essay on AI in Interactive Narrative Structures he points out that a “viewer’s anticipation of the success or failure of the plans and goals of a protagonist” really is the driving force of the traditional narrative structure. It is part of our mental state when engrossed in a story’s development. It is how we engage with fiction.
If we examine a narrative like Don Quixote we find structures that have been embraced by modern story-tellers such as Walt Disney. Disney have used the idea of believable illusion through-out all their films. So to with Miguel de Cervantes Don Quixote we encounter an allusion towards illusion. A fictional world deemed to be real in our Consciousness, and this is all because of Qualia which are sensory perceptions shared between "us" (The individual) and the stimulus (What is being experienced. That vital moment between the real and what we perceive to be real.
To examine this further, we are going to watch a film that relies on some of these theories in order to deploy its narrative, the film is called Stranger Than Fiction, the film takes us into the world of a man whose life is being concurrently written as it happens or vice-versa, as it happens it is being concurrently written.
However, both the writer and the character affect how the story is told and as the character becomes aware of his life being narrated he is able to make Subjective actions to alter the story being told, once again, however the writer has to be writing even the changes he makes so who is really unfolding the story? When they both confront each other, the writer and character, it is left untold if this is the actual ending of the story intended by the writer.
Was the writer aware that her writing was known by the real life character and if so did she intend them to meet in order to change the ending of her work?
Will Farrell in Stranger Than Fiction.