Definitely. Yakuza 6 serves as the finale for Kiryu's main storyline. However, the Yakuza franchise is known for its rich universe, and there's always a possibility of revisiting his character in some form or another.
In a Zero Kiryu x Rido Kuran fanfic regarding unlikely encounters, the initial reaction between them would be very interesting. Zero, with his hatred for vampires (despite being one), would likely be hostile towards Rido. Rido, seeing Zero as an inferior at first, might underestimate him. However, as they interact more, they could find that they have more in common than they thought, like their determination in achieving their goals, which could lead to a change in their relationship dynamic.
In fanfiction, Kazuma can be seen as a bit of a risk - taker. He is not afraid to try new things or go into the unknown. Ayano is usually very empathetic. She can understand the feelings of others easily. Their relationship in fanfiction is often based on mutual respect. They support each other through different adventures and challenges, with Kazuma being more action - oriented and Ayano being more of a thinker in many of the stories.
One interesting aspect of a Zero Kiryu x Rido Kuran fanfic could be the character development. Zero might start off as completely opposed to Rido, but as the story progresses, he could come to understand some of Rido's motives, not necessarily agreeing with them, but seeing the deeper reasons behind his actions. Rido, on the other hand, could see in Zero a worthy adversary or even a potential tool for his own plans. This could lead to a complex web of relationships and plot twists in the fanfic.
A common theme is self - discovery. Ayano and Kazuma may discover new aspects of themselves through their interactions. Another is the theme of sacrifice. They might be willing to sacrifice for each other. Also, the theme of family can be present, either their own families or them creating a family - like bond. In some fanfics, they are like family to each other, supporting and protecting one another no matter what.
One great 'kazuma and darkness fanfiction' is 'Adventures Beyond the Known'. It delves deep into their relationship as they face new challenges in a land far from their usual quests. The story beautifully portrays Darkness's unwavering loyalty and Kazuma's growth as a character.
Tappei Nagatsuki is notable for writing 'Re:Zero − Starting Life in Another World'. His writing style is able to convey complex emotions and the development of the story's mystery is really captivating.
One common theme is the 'forbidden love' aspect. Since Zero Kiryu often has a complex personality and backstory, the relationship with the reader can be portrayed as something that goes against the norms or rules within the story's universe.