
I cry for genya's death not because he was my favorite character but because I feel for sanemi ;( Sanemi fought in hopes of being able to keep demons out of his brother's life only to lose him to the very things he tried to protect him against.
Not only that, when genya ingested kokushibo's dna (which has a much higher concentrated amount of muzan's blood in comparison to the past demon parts he ate), the demon part overpowered the human part of genya thus turning genya more demon than human hence when sanemi held him, he asked why he felt like a demon.
(Now here's the painful part) Thus, when genya died, he shriveled up like a demon with only his coat/jacket left behind which was the only thing sanemi could hold and cry over instead of genya's actual body
Mirror's reflection/poker face in contrast to the sounds he makes during sex gets me every time tho