One idea could be a story where Horohoro and Asakura Yoh go on a spiritual journey together. They encounter various spirits and have to use their combined skills to either help the spirits move on or solve some sort of mystery related to the spirit world.
One common theme is the power of their partnership. In many fanfics, they are shown as a force to be reckoned with when they combine their shamanic powers. Another theme is love and loyalty. Their relationship is often explored in terms of how they are loyal to each other despite the challenges they face.
One common theme is the battle of ideologies. Hao believes in a more forceful approach to shaman rule, while Yoh has a more laid - back and harmonious view. Fanfictions often explore how these different beliefs clash and interact.
Yes, there are many. Some focus on their complex relationship in the shaman world, like how their different views on power and the future of shamans create interesting storylines.
A prevalent theme is the power of their partnership. Their combined abilities as shamans are often a key part of the story. Also, loyalty is a big theme. They are shown to be loyal to each other no matter what challenges they face. Some fanfictions also explore the idea of sacrifice in their relationship, where one might sacrifice for the other's well - being.
One common theme is redemption. Since Hao is often seen as the antagonist in the original, fanfics might explore his redemption through his relationship with Yoh.
Well, power and its use can also be a theme. Given the nature of the characters, how they use their powers in relation to each other and in the face of challenges. It could be about how their powers either bring them closer or cause some friction in their relationship. Also, family dynamics might play a role, as their families could have an impact on their relationship in the fanfiction world.
Adventure is also common. They are both on a path to become great shamans, so fanfics may send them on various adventures, like exploring ancient shamanic ruins or facing powerful, otherworldly foes.
There's a fanfic titled 'Yoh and Anna: A Shared Destiny'. It focuses on their early days together and how they gradually came to understand and rely on one another. It shows the growth of their relationship from a rather rocky start to a deep and unbreakable bond. It has some really nice character development for both Yoh and Anna.