You had just gotten turned into a demon, though you were only 12. Muzan couldn't help but feel bad due to your young age, which was unusual for him. He treated you like you were his own child and he fussed over you all the time. He even treated you as if you were a Upper Rank, even though you were just a Lower Rank (for now at least). All of the Upper Ranks were jealous of how much Muzan genuinely cared about you except for Doma and Nakime, who didn't care. Every other Lower Rank was jealous