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.
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.
The other characters in the Highschool DxD world would have a wide range of reactions. The angels might see Optimus as an unknown factor and be a bit suspicious. The fallen angels might try to manipulate the situation to their advantage. And the normal human students would be terrified at first. But as the story unfolds and they see Optimus Prime's noble actions, they could start to look up to him as a hero, much like how the Autobots are seen as heroes in their own universe.
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.
The Autobots would likely be very surprised at first. Bumblebee might be confused but also very protective. He'd probably try to keep Optimus safe from any potential threats. Ratchet, as the medic, would be both concerned and intrigued. He'd want to make sure Optimus is healthy during the pregnancy.
One possible fanfiction could be about Sentinel Prime and Optimus Prime having to work together to save Cybertron from a new, powerful enemy. They might start off with some differences in their approaches but gradually learn to combine their strengths.