Its a vampire BL. I think the ML is a vampire and is rich but is like in desperate need of blood and has been like taking blood pills. The mc is like anemic but i forgot how starts having to give the ML his blood, but is blood tastes horrible. And he also anemic so he also on the verge of passing out all the time. And the ML has to be careful not to take too much. Thats lowkey all I remember and also that the Manhwa wasnt that long like maybe mid 20s to 30 in chapters
Not My Blood
https://www.mangago.me/read-manga/not_my_blood/
no nononononoononoooooo NOOOOOOOOO