>>30710783This is a long, complicated topic that you'd need several college level English courses to properly explore, but I'm going to make a brief attempt anyways.
Fundamentally, the purpose of any functional piece of art- including a fanfic- should be to transmit an experience to the audience. Do you want your reader to FEEL a certain way? Do you want to explore a certain MESSAGE? Do you want them to simply EXPLAIN something in a new or unusual way? While these central concepts driving a story are often described as "themes", you should realize that there is a difference between the subject of the story and the purpose of one. You should always focus first on creating a strong, core experience for your fanfic before deciding on any of the characters or content, because this concept will serve as a baseline for determining whether potential storyline paths are contributive or disruptive in terms of overall plot development.
Here are some common "feeling" experiences I see driving fanfics:
-Wonder and adventure in a strange land
-Sympathy for victims of tragedy
-Amusement at comedic events
Some "message" experiences:
-Good always triumphs over evil
-The world is a shitty place and only the strong and merciless survive
-True love overcomes all adversity
Finally, some "explanations" that serve as the central experience of a story:
-Lore explaining the origins of Legendaries or the history of the Pokemon universe
-Details regarding the diet, habitat and lifestyle of specific Pokemon
The biggest issue in fanfictions where everything is correct on a "technical" level- the spelling/grammar/word choice is fluid and consistent- is a story that has a muddied purpose or one that arbitrarily switches focus halfway through. Readers may not necessarily articulate this in reviews or be consciously aware of it when reading a story, but they are going to recognize that author suddenly stopped caring about whatever experience attracted them to the story in the first place.
