A unique way to develop their relationship could be through shared dreams. Maybe they start having the same dreams where they are in a different world or time. In these dreams, they have to work together to solve problems, and when they wake up, they find that their connection in real life has also strengthened. This would be a very different and somewhat magical approach.
One interesting plot idea could be Keita and Yuzuki getting lost in a magical forest together. As they try to find their way out, they rely on each other and their relationship deepens. Another could be them having to work on a school project together where they face many obstacles but learn more about each other's strengths and weaknesses in the process.
I'm not very familiar with this specific 'kiss x sis keita x ako fanfic'. But generally, a fanfic like this might explore the relationships and interactions between the characters Keita and Ako from 'kiss x sis'. It could be about their growth, emotional bonds, or adventures within the context of the story's setting.
The theme of sacrifice also appears frequently. Sometimes one of them has to sacrifice something, like a personal dream or a friendship, for the sake of their relationship. This adds a layer of depth to the stories and makes the relationship between Keita and Ako seem more complex and real.
Typical themes might include the relationship development between Riko and Keita. It could involve their daily interactions, how they handle the unique situation of their relationship in the context of the 'kiss x sis' story.
Love and family are common themes. Since they are in a rather unique family situation, many fanfictions explore how they navigate their love for each other within the family context.
Another interesting one is 'The Promise of Keita and Ako'. In this story, they make a promise to each other that has a significant impact on their relationship. It's full of emotional moments and shows how much they care for one another in a more profound way.
There might be a lot of such fanfictions out there. However, without delving deep into that particular fandom myself, it's hard to point out exact ones. You could also check out relevant fan communities on social media platforms where fans might share their favorite fanfictions about Riko and Keita from 'kiss x sis'.
One great fanfiction could be 'Ako and Keita's School Days'. It focuses on their daily adventures at school, including how they handle the unique situation of their relationship in a school setting. There are also some really sweet moments between them that are well - written.
They could participate in a school competition together, like a sports event or a talent show. Keita and Riko would practice a lot, and during this time, they would have many sweet and funny moments. There could be some friendly rivalry with other students too. And as they strive for victory, their relationship could develop further, with Riko cheering Keita on in a really enthusiastic way and Keita being inspired by her support.