Modernism Rising in Parallel with the Popularizing of the Modern Interpretation of Psychopathology: Writing Interesting Characters by Means of Substitution
Following the basic premise that a person, as perceived by those who know him, is defined by their actions and the surmised motivations behind those actions, it can be assumed a crazy person is seen as such because the motivations behind their actions are too obscure, and possibly illogical, to be understood by an observer.
Any individual you know personally is only half of what you know them to be. Their actions are objectively true, assuming you are an average observer, but their motivations are guarantied to be falsely perceived, given that no two individuals share the same thought process.
Now, getting down to writing characters, one might begin with either the plot, the combined actions taken by the characters involved as placed on a time-line, or with the motivations. Beginning with the plot will produce a clearer linear-narrative, something more classical and theoretically salable. Starting with the characters, and following the method I am about to describe, will assuredly produce something stranger.
Starting with the plot, you simply need to work backwards, thinking, why would this character do what I, writer as God, have determined them to do. A man walking down a street might be heading to the quik-stop to buy milk for his breakfast-cereal, or he might believe himself to be barefoot and walking through a dark forest, while still on his way to buy milk for his breakfast-cereal. This is a huge difference for a character who has a head inside of which we are allowed to peek.
Starting with the characters, you begin by knowing their atypical world view, and then asking, given instigating circumstance, what would this character do.
Brass tacks, deconstruction and substitution: Begin by creating a character that is, as might be innately true, yourself. Then, alter one central feature of the character’s world view.
Assuming the interdependence and relativity of all aspects of our thought process, one small change in perspective must echo, rippling out to the farthest corners of the character’s psyche. Make this altered feature a fetish, a fulcrum around which the character swings, or a lens through which they view the world. Always ask yourself, with every line of dialogue and every action, why, given this altered feature, would this character do what my plot asks them to do? Or, if you choose to begin with the characters, simply, what would my character do?