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.
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.
I recommend 'I'm Operating on Monsters' to you. The protagonist of this novel, Guo Yi, had a dual identity. He could switch between the NPC and the player in the game, and he had a growable [Monster Space], which meant that he could make the monsters in the game grow and heal their wounds. This kind of dual identity switching played a very important role in the game. I hope you like this fairy's recommendation. Muah ~😗
One possible plot twist could be Natasha taking on Tony's role as the tech - savvy billionaire. She might use her combat skills and spy training in a new way to handle Stark Industries. For example, she could turn the company's focus more towards creating defensive technologies for the world's most vulnerable areas. Another twist could be Tony in Natasha's role. He'd have to rely more on his wits and physical abilities rather than his high - tech gadgets. He might struggle at first but then find new ways to outsmart his enemies using his intelligence in a more hands - on way.