Looking for a bl

It’s a historical supernatural bl where mc is a kid and goes into this forest to find this immortal(I think?) master to be trained under. He accepts, then when mc became an adult, the master turns into this obsessive creep who’s actually this demon that feeds off of blood I think? blah blah blah creepo takes mc away to sm mountains blah blah turns out mc is someone who could get pregnant by the demon and creepo forces mc to get pregnant w/o his knowledge. ANYWAY. Clearly, I don’t like the story lmao, but I’m bored and curious how it ended.