Also, I don't write for them, but a few other brotherly couples people write about are from Hetalia. There's Germancest which is West Germany (Ludwig)X East Germany or Prussia (Gilbert) and Itacest which is North Italy (Feliciano)X South Italy or Romano (Lovino) and America (Alfred)X Canada (Matthew).
You don't have to add them and like I said I haven't written for them, but I just thought I'd give you some couples that are brothers.