One common theme is growth. Both Mondo and Chihiro are characters that can develop a great deal, and in fanfics, their relationship often helps them grow. For example, Mondo might become more understanding and less impulsive, while Chihiro becomes more confident.
Another theme is mutual support. They often find themselves in situations where they need to rely on each other. In some fanfics, this is shown through difficult school projects or dealing with personal issues. Their relationship evolves as they become each other's pillars of support, and this theme is central to many 'ishimaru x mondo fanfic' stories.
One common theme is adventure. Given the nature of the characters, many fanfics might involve them going on quests or facing challenges together. Another theme could be romance. Since they often have a unique relationship in the original work, fanfic authors might explore different aspects of their romantic feelings towards each other.
One popular Naruto and Mio fanfiction could be a story where Mio, who might be a new character in the Naruto universe, teams up with Naruto on a mission. Maybe she has a special power that complements Naruto's abilities. For example, if she has the power to control nature in a different way than the existing characters, it could lead to interesting plot developments.
One great Mio x Minna fanfiction could be 'The Unlikely Bond'. It beautifully portrays their friendship evolving into a deeper understanding. In this story, they face challenges together on the battlefield and off, which really showcases their characters well.
It could be the way the crime is depicted or the setting of Chicago that makes it stand out. Maybe the characters or the plot twists are what's unique.