Well, in fanfiction, anything can happen. Just because it says Harry is Uryu's brother doesn't necessarily mean it's going to be a traditional brother relationship. It could be a metaphorical brotherhood, or it could be a result of some crazy plot device like a cross - over between two different universes. So, it really varies from one fanfiction to another.
Well, a Nishimiya x Ishida fanfiction often explores the relationship between these two characters. It could be about their friendship deepening into something more, like a romantic relationship. The fanfiction might focus on their interactions, how they understand each other's feelings, and the development of their bond over time.
I'm pretty sure Ishida doesn't have a niece in the manga. Usually, such significant family relations would be clearly shown or at least hinted at, but there's been no indication of this.
A key element is often their contrasting personalities. Uryu is more reserved and methodical, while Ichigo is impulsive and passionate. Their interactions based on these differences create interesting dynamics.
Ishida doesn't die. The manga follows a different trajectory for his character arc, emphasizing his personal development and relationships rather than a tragic end like death.
In this fanfiction, the plot might be that their brotherhood is a key to uniting two different factions. Harry could represent one side and Uryu the other. Their bond as brothers becomes a symbol of hope for the two groups to come together and cooperate. Along the way, they face internal and external challenges, like people who oppose their union and those who want to use their relationship for their own gain. There could also be a sub - plot about them learning about each other's cultures and abilities, which helps them grow as individuals and as brothers.
Often, the unique aspect is their dynamic. Ishida is more reserved and Orihime is very warm - hearted. In fanfics, this contrast can create interesting situations, like Ishida trying to be more open with Orihime's gentle prodding.
One popular 'ishida x orihime fanfic' is 'The Unlikely Bond'. It beautifully explores their relationship in a post - series setting, showing how they support each other in rebuilding the world.
Love and acceptance is also a prevalent theme. Nishimiya and Ishida might come from different backgrounds or have different ways of dealing with things. The fanfiction could explore how they learn to love and accept each other's differences, creating a strong and loving relationship.