Well, obviously Sunset Shimmer is one of the main characters as the story is centered around her return. Her friends from Equestria like Twilight Sparkle are also likely to be main characters. They would play important roles in how they react to Sunset's return and how they interact with her.
In addition to Sunset Shimmer and Twilight, there could be other characters like the Cutie Mark Crusaders. They might be involved in some way, perhaps they look up to Sunset Shimmer in a new light after her return and want to learn from her. And of course, the other ponies in Equestria who have to deal with the changes that Sunset's return brings.
It's also possible that some new characters are introduced in the fanfic. Maybe there are characters from the place where Sunset Shimmer has been who come with her or have some connection to her return. But Sunset Shimmer herself and her core group of friends in Equestria are sure to be the central figures in the story.
Perhaps a plotline involves Sunset Shimmer bringing back some new knowledge or a different perspective from where she has been. This could cause some conflict at first as the ponies in Equestria are not used to it, but then they gradually come to accept and even benefit from it. For example, she might introduce a new way of magic that was unknown before.
A popular one is 'Sunset Shimmer: A New Beginning'. This fanfic focuses on Sunset starting a new chapter in her life at Canterlot High. It's a heartwarming story about friendship and self - discovery, with Sunset learning to trust others more and open up about her own feelings.
Another theme is self - discovery. Sunset Shimmer is constantly finding out more about herself, her powers, and her place in the world. Fanfics may show her exploring her identity, like whether she belongs more in Equestria or the human world.
One great fanfic could be 'The Bond of Magic' which focuses on how Sunset Shimmer and Twilight Sparkle team up to solve a mystery in Equestria. It really shows their different magical abilities working together in harmony.
One great MLP Sunset Shimmer fanfic is 'Sunset's New Beginning'. It explores her journey of self - discovery after joining the main group. It shows how she overcomes her past mistakes and builds new relationships.
A common theme is her struggle with her past. Since she had a bit of a dark past in the MLP universe, many fanfics explore how she deals with that and tries to move forward. For example, in some fanfics, she has to face her old friends or enemies from her pre - friendship days.
Sunset Shimmer and Amiss could have a more complex relationship. Maybe Amiss has a past with Sunset that she doesn't fully remember. As the story progresses, Amiss could do small things to jog her memory, like showing her a familiar object or taking her to a place from her past. This would create a sense of mystery and draw Sunset closer to Amiss, while also making Anon a bit jealous, which in turn would add more layers to his relationship with Sunset Shimmer.
Some fanfics have a plotline where Sunset Shimmer and Twilight are mentoring younger ponies together. This gives them a chance to show their different teaching styles and also how they can complement each other. There are also stories where they discover a long - lost magical artifact and have to figure out what it is and how to use or protect it. These plotlines often involve a lot of mystery and exploration, which makes the fanfics really engaging.
The exploration of their friendship is vital. A great fanfic could show how their friendship started, perhaps with some initial misunderstandings, and then how it grew over time. It could include moments of them having fun together, like at a Canterlot party, as well as serious moments where they rely on each other for emotional support. The fanfic should also be consistent with the overall lore of My Little Pony.
One great fanfic could be 'Sunset's Ascent'. It delves into Sunset Shimmer's journey as she discovers and adjusts to her new Alicorn form. It has interesting character development and explores her relationships with other ponies in this new phase of her life.