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.
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'.
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.
In writing Keita's character development, explore his friendships outside of his relationship with Riko. How do his interactions with other friends influence his views on his relationship with Riko? Maybe he starts to see the uniqueness of their bond more clearly. For Riko, develop her character by showing how she copes with jealousy. Instead of just being a jealous character all the time, she could learn to trust Keita more. This change in her behavior would be a significant part of her character development, and it would also impact the overall relationship dynamic in the fanfiction.
Well, in the 'kiss x sis ako and riko fanfiction', one aspect could be how they navigate their roles within the story's setting. For example, if the fanfiction is set in the school environment, they might have to deal with classmates' reactions to their relationship. Or it could also delve into their dreams and aspirations, and how they influence each other to achieve their goals. This fanfiction has the potential to show different sides of Ako and Riko that might not be fully explored in the original work.
Riko in fanfiction usually has a lot of energy and enthusiasm. She could be the driving force behind many of their joint activities. Ako is often characterized by her kindness and thoughtfulness. She might be the one who remembers important dates or takes care of small details in their lives. They both, however, share a deep sisterly love which is a common theme in most fanfictions about them.
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.
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.
Love and affection is also a likely theme. Their relationship might be explored in terms of the love they have for each other, whether it's sisterly love or something more complex. And self - discovery could be a theme too. Through their interactions, they could be learning more about themselves.