How do the knight's actions contribute to a them if the story

Well, yes.

Explanation:

Knights are usually the main protagonist is said "stories." So their actions obviously affect the way the story rolls. For example, usually the "knight in shining armor" goes and saves a princess in distress. But what if the knight falls and breaks an ankle on the way to save the princess? Truley a tragical plot twist if i do say so myself. So all in all, a knights actions does affect the way a story unfolds.