David Miron mentioned Cold Comfort Farm as an example of change agentry.
Beware! Read the play and see older versions (Masterpiece Theatre, the
BBC's American toehold, had an excellent version about 20 years ago) for
a completely different view. The protagonist does indeed change a
"dysfunctional" family. In the beginning they are fascinating, country
eccentrics. By the end they have become boring, middle-class
suburbanites, drinking tea and talking about the weather.
I use the film Groundhog Day to illustrate a placid, complex
environment. The protagonist wakes up every morning to the same day;
the town of Punxatawny doesn't change. He becomes effective within this
environment when he begins to develop himself and when he learns the
details of the lives of many people in the town and is able to intervene
in their lives as only an omniscient person could.
Roger Putzel