How do the narrator's actions set the plot in motion?

By speaking directly to the chief, the narrator violates the trust of the villagers, which leads the villagers to plot against him.

The narrator's flashy appearance and blatant displays of wealth cause the villagers to despise him; they look for ways to force him off their land.

Paying cash to the villagers for any damage his pigs may have committed triggers a greedy response in the villagers; this causes them to trick him again and again.

By sectioning off his pigs and declaring that the villagers must repay any damage done to them, the narrator creates tension.