Often, there could be other superheroes or villains. For instance, Lex Luthor might make an appearance. He could either be an ally to the reader in trying to stop the evil Superman or have his own ulterior motives for getting involved. Another character could be Lois Lane. She might be used as a plot device, perhaps the reader has to protect her from the evil Superman or she could be a source of jealousy for the evil Superman if he has feelings for the reader.
You need to consider their different backgrounds. Superman has his Kryptonian heritage and his experiences in the Injustice 2 world. The reader could be from a more ordinary background. Show how these differences can both create friction and also draw them together. For instance, the reader might teach Superman about the simple joys of Earth life that he's forgotten in his pursuit of justice, which deepens their connection.
Lois Lane is a must - include. She can be the love interest and also a strong - willed journalist. Jimmy Olsen is also great, providing some comical relief and being Superman's friend. Lex Luthor is an obvious choice as the main villain, always plotting against Superman.
One common theme is the power dynamic. Since Superman is so powerful, it often explores how the reader character relates to that power. For example, they might be in awe of it or initially intimidated.
A good 'Superman x Reader Fanfiction' often has a strong characterisation of Superman. He should be both the powerful hero we know and also have a vulnerable side that the reader can connect with. For example, in some stories, Superman might struggle with his dual identity while falling for the reader. Also, the relationship between Superman and the reader should develop in a believable way, not too rushed.
One common theme is the struggle between Superman's heroic nature and his werewolf side. It often creates internal conflict within the character. Another theme could be the relationship dynamic between the reader (who is usually an ordinary human) and Superman in his werewolf form, like a forbidden love or a protective relationship.
One idea could be having Superman face an enemy that can manipulate time, causing chaos in Metropolis. Another could be a story where he has to deal with a powerful alien artifact that is affecting his powers. Maybe also a plot where he teams up with a new superhero from another planet.
There's also 'Superman's Secret Admirer'. In this fanfic, the reader is an ordinary person who has always admired Superman from afar. It delves into how their paths cross in unexpected ways. The story does a wonderful job of building the relationship between the two characters gradually.
Sure. Fanfiction.net also has a good selection. Look for stories rated 'T' (Teen) or lower under the 'Superman x Reader' category. These are more likely to be free of the 'lemon' content. For example, there could be stories where the reader has a special power and teams up with Superman, and their relationship is based on mutual respect and friendship rather than anything inappropriate.
In some 'evil superman x reader fanfiction', there could be a plot where the reader is the only one who can see the good that still exists deep within the evil Superman. The reader tries to bring out that good, leading to a series of intense and emotional interactions between them. It's like a battle between the evil side of Superman and the potential for redemption that the reader believes in.