It could be that Sam found out some dark secret about Dean that he couldn't overlook. For instance, if he discovered that Dean had made a deal with a really evil force in the past to save Sam's life, but in doing so,Dean had unknowingly put many others in danger. Sam, with his strong sense of justice, might feel betrayed himself first and then in turn betray Dean to set things right.
One possible reason for Sam betraying Dean in fanfiction could be a difference in their approaches to hunting. Maybe Sam gets influenced by a new ideology or a powerful entity that makes him think Dean's way is wrong and decides to go against him.
She could be a nephilim, half - angel and half - human. This would put her in great danger as both angels and demons would be after her. Sam and Dean would have to constantly protect her and figure out a way to keep her powers in check.
One great fanfiction could be where Dean and Sam have to face a unique Halloween - themed monster. Maybe a witch who uses Halloween traditions to cast powerful spells. They would have to use their wits and hunting skills to stop her before she causes chaos in a small town.
There's also 'A Hunter's Legacy'. It's set in an alternate universe where Dean and Sam face different challenges. The author does an amazing job of capturing their personalities. The story is full of twists and turns that keep you on the edge of your seat, and it really showcases the unique bond between the two brothers.
A lot of fanfictions also explore themes of sacrifice. Dean and Sam are often put in situations where they have to sacrifice something for each other or for the greater good. It shows their selfless nature. Also, the theme of redemption can be found in some, especially when they deal with characters who have made mistakes in the past.
Well, the theme of redemption is quite common. Whether it's Dean trying to make up for past mistakes or Sam finding his way back from a dark path. Love and friendship also play a role. Sometimes it's about their relationship with other hunters or people they meet. And of course, the struggle against fate. Many fanfics have them trying to break free from a pre - determined destiny.
Another characteristic is the use of the Supernatural universe elements. Popular fanfictions will have demons, angels, and other creatures from the show. They might also play with the lore in interesting ways, like coming up with new ways to kill a demon or a different origin story for an angel. For example, a fanfiction might introduce a new type of werewolf that has unique abilities. And often, the fanfictions will keep the overall tone of the show, which is a mix of horror, action, and humor. Sam and Dean's sarcastic remarks to each other are a staple of the show, and you'll often find similar exchanges in the fanfictions.
Redemption is another theme that can be found. Sometimes the characters make mistakes or have a dark past, and fanfictions may focus on how they try to redeem themselves. For example, Dean might have some regrets about past actions, and the fanfiction could be about him trying to make things right. These themes help to keep the fanfictions interesting and true to the spirit of the Supernatural series.
Good Supernatural Dean and Sam fanfiction often explores the deeper aspects of their relationship. It can look at their past traumas and how they affect their present actions. For example, Sam's time in Hell or Dean's time in Purgatory can be used to create complex and interesting storylines. The fanfic should also introduce new elements that fit within the Supernatural universe, like new monsters or new hunting techniques. And of course, the dialogue has to be believable, sounding like something Dean and Sam would actually say.
One possible plotline could be that Negan initially tries to assert his dominance over Sam and Dean. He might see them as a threat to his own 'rule' in the world of the fanfiction. But Sam and Dean, being the hunters they are, would not take kindly to his posturing. They could end up in a battle of wits and strength. Another plotline could be that Negan has some information about a powerful supernatural entity that Sam and Dean are after. So they have to form an uneasy alliance. Sam might try to reason with Negan while Dean is more on the side of being cautious and ready to fight if needed.