Killua is definitely one of the most intriguing. His journey of breaking away from the family's assassin ways and his complex relationship with his siblings and parents offer a lot of material for fanfiction. His growth and self - discovery make him a great character to write about.
Love in the context of the Zoldyck family is an interesting theme. It could be love between family members that defies the cold - blooded assassin image. Or perhaps a love story that involves a Zoldyck member and an outsider, which challenges the family's traditions and values.
The Hunter x Hunter manga is unfortunately not complete. The author has faced various issues that have led to intermittent breaks and an unresolved storyline.
The Hunter x Hunter manga has indeed concluded. However, the ending might have left some fans wanting more or with mixed feelings depending on their expectations.