One common theme is friendship. Their relationship is often explored in depth, showing how they support and care for each other. Another theme is redemption. Ash's past and his journey towards a better self is often a part of the story.
One common theme is friendship. Their strong bond as friends is often explored. For example, in many fanfics, they support each other through tough times.
One possible storyline could be that Hiro Okamura uses his technological skills to create a device that can enhance Power Girl's powers even further. This could lead to them teaming up to fight a powerful villain who is threatening the city. Another idea is that Hiro and Power Girl start off as rivals, with Hiro initially being jealous of Power Girl's natural powers. But as they get to know each other better, they realize they can complement each other's abilities and become friends and allies.
One common theme is loyalty. Their unwavering loyalty to each other is often explored, whether it's in the face of danger or personal struggles. Another is self - discovery, as they both grow and learn more about themselves through their relationship.
One common theme is friendship. Their relationship often starts as a deep friendship that has the potential to develop into something more. Another theme is sacrifice. They are often willing to sacrifice for each other in these fanfics. Also, the theme of redemption can be seen, as they help each other find a better version of themselves.
I'm not sure there are many specific fanfics just on this one aspect. However, you could start by looking on fanfic platforms like Archive of Our Own. Search for 'Banana Fish Eiji kidnapped' and you might find some relevant works. Some fanfics may explore different motives for the kidnapping, such as using Eiji to get to Ash or for some political gain within the complex world of Banana Fish.
In a fanfic, Eiji could get injured while exploring an abandoned building that has some connection to the Banana Fish mystery. Maybe he trips and falls, hitting his head. This could lead to a series of events where Ash has to take care of him, and in the process, their bond deepens as they share more personal stories while Eiji recovers.
One popular eiji and ash fanfiction might be those that explore their relationship in different settings, like in a modern AU (alternate universe). For example, a story where they meet in a college setting and their bond develops from there.