A frequent theme is secrecy. Shinobu's yandere feelings are often something she tries to hide from others, especially from Tanjiro at first. Also, the theme of protection can be seen. Shinobu may see her yandere actions as a way to protect Tanjiro from other threats, real or imagined. This can lead to some interesting plot twists as Tanjiro may not always understand her motives.
One great 'yandere Shinobu x Tanjiro fanfiction' is 'Shinobu's Obsession'. It really delves into Shinobu's yandere tendencies towards Tanjiro. The story shows how Shinobu's feelings start to cross the line from normal admiration to an all - consuming obsession. It's a really interesting read if you like this kind of pairing.
Typically, tanjirou x zenitsu fanfic often focuses on their strong friendship. It might show how Tanjirou's calmness balances Zenitsu's more excitable nature. Also, their shared experiences in the demon - slaying world are a big part of these fics. For example, they might face a powerful demon together and their bond is strengthened through the ordeal.
One popular 'zenitsu x nezuko fanfic' is 'The Unlikely Bond'. It beautifully portrays the relationship between Zenitsu and Nezuko. The author does a great job of showing Zenitsu's protective nature towards Nezuko and how Nezuko's presence calms Zenitsu in his often-fearful state.
In yandere x reader fanfics, yanderes usually display intense emotions. Their love for the reader is not the normal kind; it's more of an obsessive love. They may have a dual personality where they can be extremely sweet and loving one moment, but if they feel threatened in their relationship with the reader, they can turn very dangerous and menacing.
Fanfiction.net is also a great place to search for such fanfictions. There are many authors who post their works there. However, the quality may vary, so you might need to read the summaries and reviews to find the really good ones. Some Tumblr blogs also reblog or create 'tanjirou x zenitsu' fanfictions, so it's worth checking out Tumblr as well.
One great 'tanjirou x zenitsu fanfiction' story could be about their adventures together outside of the main plot. Maybe they encounter a new type of demon and have to rely on each other's strengths. Tanjirou's determination and Zenitsu's unique skills would combine in interesting ways to defeat the demon and strengthen their bond.
One common theme is the development of their relationship. It often shows how Zenitsu's initial fear or admiration for Nezuko turns into deeper feelings. Another theme could be their adventures together, fighting demons side by side in some fanfictions.
Well, a lot of it has to do with the potential for character development. In the original story, their interactions are limited, but in fanfics, authors can explore how they would grow closer and influence each other. For example, Zenitsu could become more confident because of Nezuko, and Nezuko could learn more about the human side of relationships through Zenitsu. It's also about the fans' love for the two characters and their desire to see them in different scenarios together.