Propp's character theory outlines eight character types that often appear in stories. The document provides an example story that features a space marine named Reaper as the hero who must defeat a monster. Reaper receives help from his sister, who provides key information, acting as the donor character. The U.S. government sends the marines, including Reaper and the false hero Sarge, on their quest as the dispatcher. In the end, Reaper is able to defeat the monster and end the threat.