I think Aqua would be an interesting character to be paired with in Pokemon fanfiction. Given her strong will and combat skills, she could be a great trainer. She might be particularly interested in Water - type Pokemon and train them to be extremely powerful. Roxas could also be a likely character. His connection to Sora and his own unique fighting style could make for an exciting story. He could be on a journey to discover more about himself while also exploring the Pokemon world. And of course, King Mickey. His leadership and magical abilities would make him a formidable ally in the Pokemon world. He could lead a group of trainers and Pokemon against a great threat, like a new type of Heartless - like Pokemon.
Riku from Kingdom Hearts and Trunks from Dragon Ball Super also make a great pairing in fanfiction. Riku has his own journey of redemption and growth in Kingdom Hearts, and Trunks has his complex backstory in Dragon Ball Super. Their combined strength and determination could be a central focus in a fanfiction story, perhaps as they face a new and powerful threat that requires both their skills and experiences to overcome.
Sora is often very popular in Kingdom Hearts fanfiction. He's the main protagonist in the game, so many fans like to write about his further adventures or different versions of him. Another popular character is Riku. His complex relationship with Sora and his own journey with light and dark make him a fascinating subject for fanfiction writers.
Another possible pairing could be Sasuke and Elsa. Sasuke has his own dark past and a brooding personality. Elsa also has her own internal struggles with her powers. They could bond over their shared experiences of having to control something within themselves that others might fear. And their cool and somewhat aloof demeanors could make for an interesting dynamic.
Naruto and Bella could be an interesting pair. Naruto's energetic and positive nature could contrast with Bella's more introverted and moody self. It could create a unique dynamic where Naruto tries to cheer up Bella and she, in turn, shows him the more complex emotional side of the Twilight world.
Well, I think Green Lantern and Rock Lee would be an interesting pair. Green Lantern's power of creating constructs with his ring could be used in creative ways along with Rock Lee's taijutsu. Also, Wonder Woman and Hinata could be paired. Wonder Woman's combat skills and Hinata's Byakugan - enhanced fighting style would make for a great combination. And Flash and Kiba with his dog Akamaru could be a fun pair, with Flash's speed and Kiba's speed - based ninja techniques.
Roxas is often a popular character in Kingdom Hearts Darkness fanfiction. His connection to Sora and his own experiences with the Organization XIII, which is related to the darkness, make him a fascinating subject. Another popular one is Axel. His complex personality and his role in the events involving the darkness in the Organization XIII storylines draw a lot of attention.
Riku often features prominently in Kingdom Hearts Dark Fanfiction. His initial struggle with the darkness in the main games makes him a prime candidate for darker interpretations. Also, Xehanort is quite popular as he is already a major villain, and fanfiction can explore his motives and backstory even further in a darker context.
Percy Jackson and Carter Kane would be a great pair. Percy is used to the Greek mythological world and its challenges, while Carter has a deep understanding of Egyptian magic and mythology. Their different perspectives could lead to some interesting teamwork, like when they face a monster that has aspects of both Greek and Egyptian mythology, such as a Sphinx with the ability to use water attacks like a Greek hydra.
Naruto and Bart could be a likely pair. Both are mischievous in their own ways. Naruto is always getting into trouble with his pranks in the ninja academy, and Bart is constantly causing chaos in Springfield. They could get up to all sorts of antics together, like pulling pranks on the other characters in both universes.
Sora is definitely one of the most interesting. His pure - heartedness and determination to save his friends are quite captivating. Then there's Riku, with his complex character arc of struggling between light and darkness.