Another theme could be adventure. Authors might place Hisoka and Tsuzuki in different fictional scenarios where they have to face challenges together. This allows for the development of their relationship within the context of the adventure, like they might be on a quest or in a dangerous world.
The theme of self - discovery is also seen. As they get closer in the fanfiction, both characters may learn more about themselves. For example, Hisoka might discover a softer side of himself through his relationship with Tsuzuki, and Tsuzuki could learn something new about his own capabilities or emotions in relation to Hisoka.
One popular theme is the exploration of their relationship's development. Since they have a complex connection in the original work, fanfictions often delve deeper into how they grow closer or face challenges together.
A common theme is the exploration of their opposing natures. Muraki is often portrayed as more of a villain or morally ambiguous character, while Tsuzuki is more on the side of good. So, the clash and attraction between these two different personalities is a big theme.
A common theme is the exploration of their opposing personalities. Tsuzuki is often portrayed as more kind - hearted and naive, while Muraki is more calculating. Fanfictions might focus on how they interact given these differences. For example, a story could be about Tsuzuki trying to understand Muraki's motives.
One common theme is the exploration of power dynamics. Given Hisoka's strength and his obsession with powerful opponents, an OC in the fanfiction might start off as a weakling he toys with and then gradually grow in power, leading to a shift in their relationship. Another theme is the idea of redemption or corruption. The OC could either try to bring out the good in Hisoka (redemption) or be influenced by Hisoka's darker side and become corrupted themselves. Also, the theme of mystery often plays a role. The OC might have a mysterious past or ability that draws Hisoka in and keeps him interested.
You can try fanfiction websites like Archive of Our Own (AO3). There are often many works related to various pairings, including Tsuzuki x Hisoka. Just search for the pairing on the site, and you'll be presented with a list of fanfictions. Some might be sorted by popularity or date updated, so you can explore according to your preference.
Another place to look could be FanFiction.net. It has a wide range of fan - created content. However, the quality may vary. When you search for Hisoka x Tsuzuki fanfiction on this site, make sure to read the reviews or ratings if available to find the better - written ones.
One common theme is the exploration of power dynamics. Hisoka is much more powerful than Gon and Killua at first, so fanfics often play with how they either try to overcome this gap or how Hisoka uses his power in relation to them.
In these fanfictions, the theme of self - discovery is often present. The male OC might be on a journey to find himself, and Hisoka becomes a part of that journey in some way. Also, themes of loyalty and betrayal can be explored. Given Hisoka's unpredictable nature, the OC might have to decide whether to stay loyal to him or not, and vice versa, which can create a lot of interesting storylines.
One common theme is the exploration of their opposing personalities. Hisoka is wild and unpredictable, while Machi is more reserved and practical. Fanfictions often play with how these differences can create either conflict or an unlikely attraction.