Wait so like- I think the main character perhaps had a crush on the younger brother and that's why he rejected the older brother back then? Because in the first chapter we see a sculpture the older brother made, and it's of two people but it doesn't have his birthmark, aka the one on the back on his waist and I think it is a birthmark because only he and his brother have those lines on their backs, but the one in the sculpture had the birthmark on the SHOULDER not his own, this is just a theory tho-