In my mind, the immature defense mechanisms really lend themselves to writing that is dramatic or relationally focused. For the most part the immature defense mechanisms are relationally oriented, meaning that it is not as good of a source of energy or plot movement for writing about a protagonist overcoming an antagonist. I would expect to see these defense mechanisms really explored in writing about individual’s day-to-day life, where the protagonist is overcoming a life event or trying to salvage a relationship.
Immediately, a demonstration of immature defense mechanisms comes to find focusing either a lovelorn protagonist suffering after a significant other they idealized left or the significant other broke her/his illusion of projective identification. In a coming of age story, a beginning point may be the use of passive aggressive defenses to begin to test who the protagnoist is in counter point to parents or society. As the story progresses, the central theme may shift to the protagonist acting out against repressive parents or society as they seek to develop their own identity and resolve their own inner conflicts. Alternatively, it could be the adolescent figuring out her/his world after a parent or role model fails to live up to the idealized image the child built of them. Fantasy and wishful thinking can serve as a starting point to a dramatic/coming of age work, where the point where the person has to confront the consequences of wishful thinking or retreating into fantasy (e.g., ignoring parent’s divorce) is the beginning of her/his journey. Passive aggressive defenses also frequently show up in romantic interactions; unable to deal with her/his own anxiety head on, the protagonist may be passively aggressive to the significant other leading to conflict in the relationship.
In writing where the success of a quest is the focus of writing, instead of personal growth or relationships (not saying that they don’t occur, they’re just not the focus), immature defense mechanisms would still likely primarily be demonstrated in the antagonist just as the pathological defenses are. A couple quick notes though about our protagonist. As with above, wishful thinking and escape into fantasy, may be the beginning of the character’s development, which when confronted with reality gives a reason to begin on the journey. In addition, the idealization of another hero from a previous era, and striving to live to that ideal may play into our protagonist’s development. Regarding our antagonists, I think of the use of immature defense mechanisms manifesting primarily in rulers. For example, I see a tyrant attempting to live up to an idealized person, ignoring the fact that person was hated and also a tyrant; instead s/he views this idealized other as a model to strive for, which repeats the tyranny cycle. Along with this would go wishful thinking, making rules, laws, decisions as if an imagined outcome would come true versus assessing the reality of a situation. An example would be King John from Robin Hood, who continued to tax people despite the fact that most of the people were being arrested or in poverty because they couldn’t bear the burden of the taxes.
Hopefully this will give us a starting point to think about 1. The focus of our writing (i.e., is it person focused or quest focused) , 2. How we can make our characters flawed, but follow them through to saving themselves (or failing because of their flaws), and 3. Now that we understand defense mechanisms, we can think about how to walk the line of making our characters real, but not intolerable (most of us can think about a person who exemplifies each of these defense mechanisms that we probably try to actively avoid).
As always, from my couch to your pen happy writing!