A frequent theme is redemption. Sometimes the Arrancar is portrayed as having a past they want to atone for, and Uryuu plays a part in that process. Also, friendship in the face of enmity is common. They start as foes but end up being friends or something more. It's about breaking down the barriers between their two groups. For example, in some fanfics, Uryuu might help the Arrancar understand the value of human life, which is a Quincy concept, while the Arrancar shows Uryuu a different perspective on power and survival.
There were two reasons why Ishida Sansei refused to drink the water. First of all, some people thought that he refused to drink water because persimmons were prone to phlegm. He did not want to die with unclean things, and persimmons were not good for the body. Secondly, Ishida Sansei believed that ambitious people should cherish their bodies and be responsible for themselves even when they were on the verge of death. He refused to drink water to maintain his self-discipline and cherish himself. These two explanations reflected Ishida Mitsunari's characteristics and self-cultivation as an ambitious person.
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.
Well, 'Shared Secrets' is a great one. It focuses on Fem Uryuu discovering a secret about Ichigo's inner Hollow that no one else knows. This leads to a series of events where they have to trust each other more than ever. And then there's 'The Path of Redemption'. Here, Fem Uryuu has made some mistakes in the past and Ichigo helps her find her way back to the right path. It shows a different side of their relationship, with Ichigo being the guiding force.
The contrast in their personalities. Ichigo is hot - headed and impulsive, while Fem Uryuu is often more reserved and intellectual. When combined in fanfiction, it creates a dynamic relationship full of potential for interesting storylines. For example, they can have arguments over the best way to deal with a Hollow, which makes for great drama.
One popular uryuu x loly fanfiction might be 'The Unlikely Bond'. It focuses on how their different personalities interact and gradually form a deep connection. The story shows Uryuu's calm and collected nature contrasting with Loly's more energetic and impulsive side, which makes for an interesting dynamic.
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.