
I remember reading this one bl manga and one of the main guys had a unrequited crush (obviously lol) on his father/step father or something like that. I think both had a unrequited love/sexuality problems and they became friends because of that. The two men later became a couple
I found it and he had a past crush on his older brother not his father. https://www.mangago.zone/read-manga/bokura_ga_koi_wo_ushinau_riyuu/
https://www.mangago.zone/read-manga/okane_nara_arimasu/ isnt this the one u talking about :o? its translated !
I think Sebastian encountered this man when he was on his own investigating people during one of Our Ciel's missions or Sebastian sneaks out at night sometimes to have fun since demons don't need to sleep. Maybe this guy is a one night stand of Sebastian's that died like beast did? Maybe that's why the man called Sebastian a "demon". He probably meant it literally and figuratively? There's going to be a lover's quarrel in the next chapter lol