First time asking here but I came across someone from reddit asking about a yaoi of a cute uke that grew up to he a buff uke and his boyfriend/crush came home and didn't recognize him so he pretended to be the big brother of the cute uke his crush was there to meet.

I hope you can help.

I'm not sure about the one you are looking for, but Houtou Musuko to Koi no Ana has a similar plot. But instead of pretending he was the big brother of the cute uke, the story is about a guy that feel in love with a girl as a child only to find out that the buff guy he met again (who he thought was the brother of the girl) is actually the "girl".

I've read this one but sadly, it's not what I was looking for. Thanks anyway.