The report of the study stresses the intractability of characters, and goes to lengths to support the "experience of characters contributing to or rebelling against the author's vision of a story." What seems particularly interesting about this phenomenon is not just that the characters have agency, per se, but that their actions open up whole lines of narrative and perspectives on the world to which the author might very well not have access without the particular agency afforded by the character's traits, experiences, and activities.
There seem to be several implications here. One might involve identity maintenance; I may not be able to buck socially desirable response patterns in particular situations, etc., while my character may. This suggests that while we preserve our habitual identities, our characters make us new personalities, or personality extensions. And these may help us get to all those pesky thoughts that hover beyond the edges of what we might otherwise consciously be able to write about.
In research into visualization, mirror neurons, and imagining actions, brain activity has been shown to correspond to the brain activity that would actually occur if an item or action visualized or witnessed or imagined was actually being seen or performed (Kosslyn et al. 2001; Oberman et al. 2007). Applied to intractable characters, this could suggest that instead of being merely symbolic representations compiled from the parameters of our stories, the exploratory projection of intractable characters may be creating a simulation that involves a frame of mind that’s not necessarily the one you would be inhabiting were you not imagining a character. And possibly even that these personality extensions may help us transcend the habitual limits, say, of being an agreeable person, or a graceless person, or a loud or quiet person. I think I have some jobs for some characters.
Kosslyn, S. M., Thompson, W. L., Wraga, M. J., & Alpert, N. M. (2001). Imagining rotation by endogenous versus exogenous forces: Distinct neural mechanisms. NeuroReport, 12, 2519-2525.
Oberman, L. M., Pineda, J. A., & Ramachandran, V. S. (2007). The human mirror neuron system: A link between action observation and social skills. Social Cognitive and Affective Neuroscience, 2(1), 62-66.
Taylor, M., Hodges, S., & Kohányi, A. (2002-2003). The illusion of independent agency: Do adult fiction writers experience their characters as having minds of their own? Imagination, Cognition, and Personality, 22, 361-380.