Honestly, I've always found this trope cringe in general. I tried to read a couple of manga out of curiosity but I see it as if the author is just trying to satisfy a fetish (brother x brother), but trying to make it legal and more ethical without a blood relationship. Some stories are even nice but I can't take them seriously because this concept is crazy! I can't conceive how two people who grow up together as brothers since they are children start to see each other in a romantic light... And even in cases where they meet as grown-ups, why would you fall in love with the person who's supposed to be your "brother" of all the people in the world?? This just doesn't sound right... But I know it's just fiction and I'm not judging anyone of course, it was just my opinion.
I don't know why but I think my comment was cut lol. I was saying that their dynamics makes "some sense" at least since they didn't grow up together, but times ago I happened to read this manga (just because I like the author), and these two were like in kindergarten when they became brothers, because their parents started dating, and when they started to express their feelings I was like hell naaahh I'm out!!
OK LISTEN, it’s not that deep since theyre not blood related BUT WHEN THE TOO SAID “i wonder why my little brother is so cute” i legit jumped like no u cant be having sex and saying little brother at the same time