One great Ichika x Kanzashi fanfiction is 'A New Bond'. It focuses on their relationship development in a post - war scenario in the Infinite Stratos world. The story beautifully captures their growing understanding of each other.
One of the best elements is the exploration of their different personalities. Ichika is often portrayed as the brave and somewhat clueless hero, while Kanzashi is more reserved and intelligent. Their interactions based on these traits can be really interesting.
In a fanfiction, Ichika and Houki could have a moment where they confess their feelings for each other. Maybe it starts with a simple misunderstanding. Houki sees Ichika with another girl and gets jealous. But then Ichika clarifies that he only has eyes for Houki, leading to a very sweet and heartwarming confession scene.
One possible fanfiction could be about Ichika and Chifuyu going on a training mission together. They face some unexpected challenges during the mission, which forces them to rely on each other more than ever. This could lead to a deeper understanding and bond between them.
The contrast between their characters is one reason. Ichika is the typical male lead who is learning and growing in the world of IS, while Tabane is this super - intelligent and somewhat mysterious inventor. Their interactions can be full of surprises.
One interesting fanfiction could be where Ichika discovers a hidden side of Tabane. Maybe she has a secret project related to the IS technology that only Ichika gets to be a part of. This could lead to a lot of adventure and some budding romance as they work together closely.
An idea could be that Ichika and Houki are paired up for a special project at the academy. They have to design a new type of mech together. During the process, they argue about different design aspects but in the end, they come up with an amazing design. This experience makes them realize how well they work together and how much they care for each other.
One interesting plot could be a time - travel fanfiction. Ichika somehow gets sent back in time and meets a younger Chifuyu. They start to form a bond that is different from their relationship in the present. As Ichika tries to find his way back to his own time, he realizes how much Chifuyu means to him, and when he finally returns, their relationship has changed in a way that they both start to explore their romantic feelings for each other.
When writing, focus on his internal struggle. Show how his thoughts and emotions are changing as he becomes darker. You can also introduce new characters or powers that enhance the dark aspect of the story. Maybe give him a power that has a dangerous side - effect that slowly corrupts him. And don't forget to keep the Infinite Stratos world - building intact while adding your own dark twists.