Sweet but short. I would really like to read a more likely scenario in which the relative needs to be talked into it rather than automatically being in love, too.
Keiichi and Kaname used to be cousins, but they became brothers when Kaname was adopted into Keichi's family after his parents died in a car accident. The two of them have always gotten along well, but lately Kaname is acting strangely. He has become so cold and distant that Keiichi begins to wonder if his adopted brother hates him for some reason.