The relationship would likely become more intense. They would have to rely on each other more, and their bond would deepen as they are about to become parents. Inuyasha would probably become more protective of Kagome.
There could be a fanfic that delves into their backstories more. For instance, exploring Sango's past as a demon slayer in greater detail. How she overcame her family's tragedies and how that has shaped her. Inuyasha and Kagome could be part of this exploration, learning more about Sango and in turn, Sango learning more about their own complex pasts and how they are dealing with it.
Kagome would probably be shocked at first. Then she would start yelling at Inuyasha, demanding to know why he's doing this. She's not the type to just sit there and take it.
A favorite moment could be when Inuyasha saves Kagome from a dangerous demon in a fanfic. His quick reflexes and determination to protect her show the depth of his feelings. Sango might be there to provide backup, and the way they all work together in that intense moment is really exciting.
Another fanfiction concept could be set in an alternate universe where they are all students in a school. Inuyasha might be the troublemaker, Kagome the studious one, and Sesshomaru the aloof and brilliant student. There could be a mystery at the school that they have to solve together, and through this, they form an unlikely friendship.
Sesshomaru is an enigma. In fanfiction, his cold exterior and his pride as a full - demon are prominent. He initially sees Inuyasha as a weak half - breed, but as the story progresses, he may come to respect Inuyasha's growth. His relationship with Kagome can also be an interesting aspect. Sometimes he's indifferent to her, but other times he might be intrigued by her powers and her ability to change Inuyasha.
In fanfiction, the relationships between Inuyasha, Sesshomaru and Kagome can be very diverse. Some fanfictions might focus on Inuyasha and Kagome's relationship, which is often a complex mix of love and adventure in the original series. Their relationship is full of bickering and mutual understanding. While Sesshomaru, being Inuyasha's brother, may be depicted in fanfiction as having a more aloof or even begrudging respect for Kagome. He might interact with her in unexpected ways, perhaps even having a slow - building friendship or an unusual alliance.