One common theme is adventure. Since Killua is from the Hunter x Hunter world which is full of dangerous quests and exploration, many fanfictions involve the reader joining him on his adventures. For example, they might go on a journey to find a rare treasure or explore a mysterious and dangerous place.
A theme that's also quite prevalent is the idea of helping Killua overcome his family - related traumas. The Zoldyck family has a dark and complex history, and in fanfictions, the reader can play a role in helping Killua deal with his past, whether it's his relationship with his parents or his training as an assassin. This adds a layer of depth to their relationship and the overall story.
One common theme is adventure. Since Killua is from the Hunter x Hunter universe which is full of dangerous quests and exploration, many 'killua zoldyck x oc fanfiction' stories involve the OC joining him on these adventures. Another theme is friendship evolving into love. The OC and Killua start as friends or allies and then their relationship deepens over time.
One common theme is friendship. The SI OC often forms a deep bond with Killua, and they go through various adventures together, relying on each other. Another theme could be self - discovery. As the OC is in a new world with Killua, they learn more about themselves.
One common theme is growth. The reader often starts off as a relatively inexperienced character, and through their interactions with Killua, they grow both in terms of their skills as a hunter and in their personal relationships. For example, they might learn how to better control their nen abilities with Killua's help.
One common theme is adventure. Since 'killua' is from the 'Hunter x Hunter' universe which is full of exciting and dangerous adventures, many fanfics will have the reader character and Killua going on quests together. Another theme is friendship and trust building. Killua has a complex personality, and fanfics often explore how he gradually opens up to the reader character, forming a deep bond of trust.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3) or FanFiction.net. AO3 has a large and diverse collection of Killua Zoldyck x Reader fanfictions. Just use the search function and type in 'Killua Zoldyck x Reader' and you'll get a bunch of results. Some are really well - written with great character development and interesting storylines.
One common theme is adventure. Since the Hunter x Hunter world is full of dangerous and exciting places, fanfics often have the reader and Killua going on quests or exploring new areas. Another theme is friendship. They start to build a strong bond as they face different challenges together.
Well, a very frequent theme is the exploration of power dynamics. Given Illumi's powerful and somewhat intimidating nature, the fanfictions often look at how the OC fits into that power structure. It could be that the OC is weak at first and has to grow to be on par with Illumi, or the OC might have a unique power that changes the balance. Also, love and redemption are common themes. The OC might bring out a sense of redemption in Illumi, or they might fall in love in a rather complex and interesting way considering Illumi's character.
One popular 'killua zoldyck x oc fanfiction' is 'A Hunter's Bond'. It focuses on the relationship between Killua and an original character. The story develops their bond through various adventures in the Hunter x Hunter world. Another one is 'Killua's New Companion' which shows how the OC impacts Killua's growth and decisions.
Friendship is a very common theme. Since Gon and Killua have such a strong bond in the original work, fanfictions often explore different aspects of their friendship, like loyalty and mutual understanding.
A common theme is family. Given their complex family situation in the original story, fanfictions often explore how Killua and Alluka's relationship affects and is affected by their family. Another theme is protection. Killua is very protective of Alluka, and this is often a central aspect in these fanfictions.