One interesting 'Hunter x Hunter' romance fanfiction could be one where Gon and Killua's relationship takes on a more romantic undertone. It might explore how their deep friendship could potentially develop into something more. Another could be a story that pairs Kurapika with a new character in a romantic adventure within the 'Hunter x Hunter' world.
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.