We don't really know who Buster is just from this title. He could be an ordinary person whose story has been told to illustrate a particular point about having a'mal heart', whether it's about his character flaws or some sort of misfortune he has faced.
No. 'The Ballad of Buster Scruggs' is not based on a true story. It is a fictional creation by the Coen brothers, filled with their unique brand of dark humor and Western - themed storytelling.
One possible fanfiction could be about Harry Potter finding the Buster Sword in the Forbidden Forest. Maybe it was left there by a wizard from a far - off land who had visited Hogwarts long ago. Harry discovers its unique powers and has to learn how to use it while still dealing with Voldemort's threats.
Well, 'naruto mega buster fanfiction' could be about a character in Naruto who discovers or creates a mega buster. This could lead to all sorts of new storylines. For example, they might use it to fight a powerful new enemy, or it could cause some sort of conflict among the ninja clans because of its power. Maybe it's a story that focuses on how this mega buster changes the balance of power in the Naruto world and how the different characters react to it.
The last story in Buster Scruggs has no one fixed meaning. It could be seen as a reflection on human nature, or a metaphor for the journey of life with all its uncertainties and surprises.