Well, Hisoka's origin story in Hunter x Hunter is quite interesting. He hails from Meteor City, a place that's more like a dumping ground for the unwanted. Growing up there, he was exposed to all sorts of things that normal people wouldn't experience. His love for fighting strong opponents probably stems from the fact that in Meteor City, strength was the only way to get what you want. Hisoka's nen abilities are also a product of his environment. He's constantly evolving and seeking new challenges, which is likely a trait he developed while growing up in a place where only the fittest survive.
One great 'Hunter x Hunter Chrollo Fanfiction' is 'Chrollo's Redemption'. It explores an alternate path for Chrollo where he tries to atone for his past sins. The story has really good character development and the author does an amazing job of getting into Chrollo's psyche.
There's a fanfic called 'Hisoka's Obsession with Machi'. It delves into Hisoka's perspective. He is constantly intrigued by Machi's skills and her cold exterior. The story has some interesting scenes where Hisoka tries to get closer to Machi, and Machi is both repelled and fascinated by him at the same time. It's a really engaging read.
A prevalent theme is the struggle between good and evil. Kurapika is often seen as a symbol of good, while Chrollo represents evil. Fanfictions play around with this dynamic, sometimes blurring the lines between the two. Also, the theme of trust is common. Given their history, it's interesting to see how fanfiction authors make them build trust in each other, like in a story where they have to rely on each other's skills to survive a dangerous situation which spans over a long journey.
He could be portrayed as a rival. Since Chrollo is such a powerful and complex character in Hunter x Hunter, his brother might be someone who challenges him in different ways, like competing for power or influence within the world of the story.
Chrollo's brother in fanfic can be a really interesting character. He might have similar powers or a completely different skill set. For example, he could be a master of a different type of nen ability that contrasts with Chrollo's. This could lead to some really cool plot lines where they either team up or are at odds with each other.
Well, power dynamics is a common theme too. Since they are in the Hunter x Hunter universe, the fanfictions often play with how their respective powers interact and how that affects their relationship. There's also the theme of identity. They might struggle with their identities as individuals and as brothers in a world full of hunters and powerful foes. And love, not necessarily romantic love but the love between brothers, is also a recurring theme, showing how their love for each other can overcome various obstacles.
One great fanfic is 'The Unlikely Bond'. It delves into the complex relationship between Hisoka and Gon. The author beautifully captures Hisoka's twisted fascination with Gon and Gon's naivete in dealing with it. It has some really interesting plot twists that keep you hooked.
I really like 'Hisoka's Obsession'. It shows Hisoka's fixation on Gon in a more detailed and somewhat darker way. It adds layers to Hisoka's character while also developing Gon's reactions to Hisoka's strange behavior. The writing style is engaging and it's easy to get lost in this alternative take on their relationship.
One popular Hisoka fanfiction might be those that explore his backstory. Since in the original 'Hunter x Hunter' his past is quite mysterious, fanfictions often fill in the gaps. For example, there could be stories about his early days as a Hunter and how he developed his unique nen abilities.