A great plot idea could be that Nezuko develops a new power that only works when she and Tanjiro are in close proximity. This power could be crucial in fighting a powerful upper - rank demon. For example, she might be able to create a protective shield around them both. Another could be a fanfiction where Tanjiro and Nezuko are invited to a demon slayer gathering in a far - off land. There, they meet other slayers from different regions and learn new techniques. Along the way, they also have to deal with some demons who are trying to infiltrate the gathering.
Their relationship can be further explored by focusing on their non - verbal communication. Since Nezuko can't speak much as a demon, the looks they exchange, the way Tanjiro gently touches her head to reassure her, these small gestures can be delved into. For example, in a dangerous situation, Tanjiro's glance at Nezuko could convey a whole world of trust and protection.
One idea could be an OC who has a unique breathing style that combines elements from different existing styles. For example, a mix of water and flower breathing, which could create beautiful yet powerful attacks. Another could be an OC who is a demon but has retained some of their humanity and tries to find a way to coexist with the Demon Slayers. Maybe they form an unlikely alliance with a slayer to fight against more evil demons.
One popular theme is their relationship growth. Writers often explore how Tanjiro and Nezuko's bond changes as they face different challenges in the demon - slaying world. It could be about how Nezuko's demon nature affects their connection.
One idea could be a male OC who has a unique breathing technique passed down in his family. For example, a 'Star Breathing' technique that allows him to move as swiftly as a shooting star and his attacks are like constellations. Another plot could be that the male OC is a demon slayer from a foreign land, bringing in different fighting styles and cultural elements to the Demon Slayer Corps. Or perhaps he has a special bond with a demon that he is trying to redeem instead of killing.
Perhaps in the fanfiction, Oyakata-sama gets cursed, and Tanjiro is the only one who can sense it. Tanjiro then embarks on a journey to find a cure, with Oyakata-sama's health deteriorating. This would create a lot of tension and an opportunity for their relationship to develop further.
In a Nezuko crossover with the Naruto universe, Nezuko could be an enigma to the ninja world. Her demon form might be seen as a powerful and dangerous new jutsu. Also, a crossover with the One Piece world could be interesting. Nezuko might end up on the Grand Line and her powers could either be a great asset or a cause for concern among pirates and marines.
Nezuko remains alive in the Demon Slayer manga. The author chose to keep her alive as she is an important character with a vital part to play in the overall narrative.
Well, he might travel back in time and end up being mistaken for a demon himself because of his unique ice powers. This could lead to all sorts of misunderstandings and battles. Or perhaps he travels back to the time of the first demon slayers and has to train with them using his modern - day knowledge of fighting demons. He could also travel to a time when a major demon - slayer organization was in its infancy and help shape it into a more effective force against demons.
One idea could be that the Demon Slayers are brought into the world of My Hero Academia. Tanjiro could learn about quirks and try to figure out how to use his skills in this new environment. Maybe some of the demons also gain quirks which makes them even more dangerous.
One idea could be that the male OC has a unique power related to sound. He can use different frequencies to either paralyze demons or disrupt their attacks. For example, in a battle against a powerful demon in a forest, he uses the natural echo to amplify his power and gain an upper hand.