Responses
Omg. This sounds so familiar! I’ll do some digging
Someone found it. It’s Ijiwaru Shujin no Mitsugi ni Torokeru (Yaoi) I forgot about the maid thing so I wrote secretary which is why I had such a hard time finding it.
I remember that they met in college, one was the heir to a family where they have a special constitution where they have pheromones to seduce everyone and the uke acted like he wasn’t affected and became a secretary to stay by his side. It’s not omegaverse and the first manga was about the younger brother being brought back to the family and learning about this and his caretaker knew him when he was young but he didn’t remember and thought he was just acting for the family (also yaoi)