Well, at first, they might be in denial about being brothers. Draco, with his pure - blood pride, and Harry, who has his own set of values. However, they could start to see similarities in each other. Draco might notice Harry's courage and Harry could see Draco's loyalty to his family (even if it's a different kind of family now). They could end up teaming up to solve mysteries within Hogwarts, and in the process, their relationship could transform from reluctant acceptance to a real, deep brotherly bond.
Inosuke survives throughout the manga. The story doesn't have his death as part of the plot. His character remains active and plays a significant role until the end.
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.