There’s a Korean BL I remember being popular on here about a guy who had to crossdress as a kid while pretending to be an old man’s relative(?? Not sure about that part) and while he was there there was also another boy there with him(the ML). These two later grow up with the MC trying to move on from his past while the other is still desperately looking for him, and they come across each other while the MC is working at a bar and the ML mentions that he looks like the girl he has been looking for the whole time. I’ve been trying to find it for a bit, and I just can’t seem to remember the name of the BL. Would any of you happen to know the BL I’m talking about?
Hi, it seems the plot of Reunion even though they didn't meet as kids but in their 20s. https://www.mangago.me/read-manga/reunion/
Even if it's not the BL you're searching for I recommend you read it, it's amazing imo!

Hello, I’m looking for an omegaverse Korean BL in which the MC’s favored dominant omega brother ran away from his arranged marriage with MC’s crush and now the MC has to take his place. He’s taken to his fiancé’s residence, meets the dominant alpha fiancé, and is forced to stay inside this mansion. It’s later revealed there’s succession drama going on, with the fiancé’s beta brother is trying to find a way to become head of the family over his brother. Thank you in advance!
I think you might be thinking about Quo Vadis, Domine?
Yes, thank you!