
Maybe some person will think I'm crazy xD, but what's wrong with the FL falling in love with his brother (ML) after all they're not blood related? , even in real life there are ppl who fall in love with their real siblings , for example this couple who even got children even though they're both siblings born from the same parents ..... ┑( ̄Д  ̄)┍

So the story I think is some like this?
The blond guy (seme I think?) ask for ain (the gay masseur) then the blond guy didn't clean up the dead body in the house (after all ain is supposed to be blind) but he didn't know that ain is just acting blind, then the blond guy noticed (maybe) that ain is acting weird and that ain is just Acting blind and so the start of their relationship??

Yes I think the story will be like that too.
Also you reminded me of an Indian movie on Netflix, a blind pianist witnesses a murder/body at the house he was hired to play at but since he is blind he has to ignore it but eventually cannot and tries to report it and the houseowner catches on due to his odd behavior
In ch.4 where the master said
" yue, from the moment I first saw you, I decided... That you'd be my sheath"
Me: ..... Sheath.... Is it the sheath I'm thinking??