Polyphony

From RhetorClick

The literary term "polyphony" was coined by Mikhail Bakhtin. When using polyphony, an author does not write from a single voice or vision: rather, the characters and the narrator express a variety of voices and points of view, which often conflict and certainly do not always form a coherent picture.

Source: http://en.wikipedia.org/wiki/Polyphony_%28literature%29