A common theme is the exploration of the unknown. Since Mephisto is often associated with mystery, fan fictions usually involve the reader character delving into Mephisto's dark and magical world.
One great piece of mephisto x reader fan fiction is 'Mephisto's Encounter' which has an interesting plot where the reader character gets involved in Mephisto's mysterious world. It's full of vivid descriptions and engaging dialogues.
One common theme is friendship evolving into something more. Since they start with a pre - existing relationship in the game's lore, fanfics often explore how that relationship can deepen into a romantic one.
Well, 'Love in the Courtroom' is another great one. It combines the courtroom drama aspect that is so characteristic of the Phoenix Wright series with the budding relationship between Phoenix and Iris. The fanfic is full of suspense, just like in the games, and at the same time, it weaves in the romantic elements very skillfully.
You should also include some foreshadowing. Drop little hints throughout the story before the big betrayal. Maybe Iris has been acting a bit strange lately, or there have been some small disagreements between her and Ash that gradually build up to the ultimate betrayal. This will make the betrayal seem more natural and less out - of - the - blue for the readers.
One possible plot could be that Dragonite gets separated from Iris during a dangerous adventure. Iris is desperate to find it and Dragonite is trying to make its way back to her. Along the way, Dragonite has to face various challenges and meets other Pokémon who either help or hinder its journey back to Iris.
One great 'noct x iris fanfic' is 'The Bond Beyond Worlds'. It beautifully portrays their relationship with a lot of emotional depth. The author does an amazing job of creating scenarios where Noct and Iris interact in a way that feels both true to their characters and also very engaging.
One possible scenario could be that in this high school fanfiction, Ash and Serena form a team to compete against Iris in a Pokémon battle tournament organized by the school. Ash's experience and Serena's elegance might create a unique synergy that gives them an edge, while Iris with her strong and wild Pokémon could pose a great challenge. Maybe there are also some romantic subplots between Ash and Serena as they battle side by side, and their relationship might grow deeper during this rivalry with Iris.
The plot needs to be engaging. It could involve elements from the original games, like courtroom battles, and then add the romantic aspect between them. For example, a case that somehow brings them closer together in an unexpected way. It should also have a good flow, not be too rushed or too slow.