Sure did. But the ending left some fans satisfied while others had mixed feelings. It all depends on your expectations and interpretation of the story.
First, study their characters. Know their personalities, backstories, and how they interact in the original story. For example, Shinobu is often calm but has a hidden fierceness, and Giyuu is a bit of a loner. Then, come up with an interesting plot. It could be about them going on a joint mission where they face a new type of demon. Keep in mind their relationship dynamics as you write.
In a Giyuu x Shinobu fanfic, the setting and plot can vary widely. Some might be set during the main events of the Demon Slayer universe, with them facing demons together. Others could be more of an alternate universe story, where they meet under different circumstances, like in a modern - day high school AU. The fanfic could also delve into their backstories and how those experiences shape their relationship. For instance, Shinobu's past with her sister could play a role in how she opens up to Giyuu, and vice versa for Giyuu's own traumas.
I would recommend 'Whispers of the Heart' for Giyuu x Shinobu fans. This fanfic focuses on their unspoken understanding. It's full of small moments that build up their relationship, like when Shinobu leaves a small flower on Giyuu's doorstep as a sign of her care. Also, 'Shadows and Sunlight' is worth checking out. It has a great plot that involves them having to go on a secret mission together and how that journey changes their relationship from colleagues to something more intimate.
Well, the 'kny light novel' often has a unique narrative style. It might have detailed character development and an engaging plot that can draw readers in.