Perhaps a fanfiction where Tsubasa time - travels back to the early days of football in Japan. He meets the pioneers of the sport in his country and uses his modern skills and knowledge to inspire them and help develop the game even faster than it actually did. He could also face challenges in this different era, like dealing with more primitive equipment and different rules interpretations.
Well, perhaps a plot where they are transported back in time to an era when magic was first discovered. They have to learn how magic was initially harnessed and face challenges from the past. They could also find out secrets about their own families or the origin of their magic. This would involve a lot of exploration and discovery for both of them, and they would need to support each other through it all.
Well, they could be transported to a modern - day Earth and have to adapt to a completely different culture while still maintaining their relationship. It would be funny to see them deal with things like smartphones and cars.
One idea could be exploring the backstory of the captain before the promise was made. Maybe there was a tragic event in their past that led them to make such a solemn vow. Another could be a situation where the captain has to break the promise to save their crew, and then deal with the moral and emotional consequences.
One idea could be a crossover where the Naruto characters interact with the Shinigami captains in a battle against a common enemy. For example, Naruto's unique jutsu combined with a Shinigami captain's zanpakuto abilities would make for some epic fight scenes.
One plot idea could be that Tinkerbell is sent on a mission by the fairies to steal a magical item from Captain Hook. But during the process, she discovers that Hook has a tragic past that led him to his villainous ways. This makes her question whether he's truly all bad.
One plot idea could be an OC who is a scientist during World War II and teams up with Captain America. They could work on some top - secret projects together. Another is an OC who is a foreign agent sent to assess Captain America's abilities and ends up becoming his ally. Maybe an OC from the future who travels back in time to help Captain America prevent a major catastrophe that wasn't in the original timeline.
One frequent theme is the exploration of new worlds. Naruto enters the world of Captain Tsubasa and has to adapt. Also, competition is a big theme. There are often tournaments or games where the characters compete against each other, showing off their unique powers and skills from their respective universes.
One good Captain Tsubasa Sanae fanfic could be 'Sanae's Dream Run'. It might focus on Sanae's journey in the football world, her growth as a character, and her relationships with other characters from the series. It could have exciting match descriptions and her emotional development throughout the story.
One idea could be inserting yourself as a new recruit in the Howling Commandos. You could have a special skill, like being an expert in decoding enemy messages. Then, you get to interact with Captain America and the team, facing challenges together and forging strong friendships. Another plot could be that you are a scientist in the same era as Steve Rogers. You accidentally discover a new element that could enhance the super - soldier serum. This draws the attention of both Captain America and the bad guys, leading to a race to protect or steal your discovery.
One idea could be that Captain Phasma and Finn are forced to team up during a mission gone wrong. They start off distrusting each other but as they face various challenges, they gradually come to respect one another's skills. For example, they might have to fight against a new and powerful enemy force that neither of them can handle alone.