Well, in Sailor Moon x Reader fanfiction, a common trope is the transformation. The reader often discovers their own powers and goes through a cool transformation sequence, similar to the Sailor Scouts. Also, the 'Secret Identity' trope is popular. The reader might have a secret identity that they have to keep from the other characters while still being part of the group. And of course, the 'Power Struggle' trope, where the reader has to deal with their newfound powers and the responsibilities that come with them.
One popular trope is the 'fish out of water' story. For example, a Star Wars character like Luke Skywalker could end up in the Sailor Moon world and have to adapt to the very different environment and magic system. Another is the 'power - up' trope. A Sailor Scout might gain new powers inspired by Star Wars technology or the Force.
One popular Sailor Moon reader fanfiction could be those that explore new relationships between the Sailor Scouts. For example, some might focus on a deeper friendship between Sailor Moon and Sailor Mars. Another type could be ones that give a different origin story to the villains, making them more complex characters. There are also fanfictions that place the Sailor Scouts in modern day situations that are completely different from their original story settings.
Well, a common trope is the 'roommate' situation. In reader x reader fanfiction, it can lead to a lot of fun and sometimes awkward moments as the two readers live together. There's also the 'fake relationship' trope. They might pretend to be in a relationship for some external reason, like to make someone else jealous or to get into an exclusive event. And the 'reunited after years' trope is also seen often, where the two readers meet again after a long time apart and old feelings resurface.
One popular trope is the 'new in town' trope. The reader character is new to Derry, and then they meet the Losers' Club or Pennywise. It sets up a great scenario for character interactions. For example, the reader might be intrigued by the strange happenings in town and get drawn into the story.
Another popular trope is 'hurt/comfort'. In Hiccup x Reader fanfiction, it often involves Hiccup getting injured during a dragon fight or some other dangerous situation, and the reader character taking care of him. This trope allows for a lot of tender moments between the two characters and can really deepen their bond. It also shows the caring side of both characters, with the reader being nurturing and Hiccup being vulnerable yet trusting.
There's also the 'co - workers to lovers' trope, especially considering Spencer's work environment. They start as colleagues, sharing cases and experiences, and then their relationship evolves into something more romantic. This trope allows for a lot of professional and personal interactions to be explored.
One popular trope is the 'caretaking' trope. The other characters in the story, usually the main character from the original work, will take care of the sick reader. They might bring soup, medicine, and stay by the reader's side to comfort them.
One popular trope is the 'forbidden love' trope. It could be that Silver is from a different world or group, and the relationship with the reader is not allowed in some way. This creates a lot of tension and drama in the story.
The 'mystery' trope can be found as well. Grell himself is a rather mysterious character, and in Grell x Reader fanfictions, the reader may be drawn into a world of secrets that Grell holds. Maybe the reader has to figure out Grell's true intentions, or there could be some mystery surrounding their connection that unfolds throughout the story. This can add an exciting element to the fanfiction.
The 'Forbidden Love' trope is quite common. Given Castiel's angelic nature and the rules in the Supernatural world, a relationship between him and a human reader might be seen as forbidden. This adds an element of tension and drama to the story. Also, the 'Healing' trope, where the reader helps Castiel heal from his past traumas or vice versa, is often used. They support each other through difficult times, which makes for a heart - warming story.