Wow,that's so tough,many come to mind especially Alphonse (Ed's Younger brother) from FMA..and even especially Mokuba from Yu-Gi-Oh!,but in this case I'll go with Mokuba,as Mr.Kaiba cares for him,he cares Kaiba,I remember in an episode when they were younger Mokuba was aware that Kaiba wanted the Blue Eyes White Dragon so he stayed up and attempted to draw The Blue Eyes Card for his brother!,I thought that was really cute!,and how he always looks up Mr.Kaiba,It's really a cute brother-brother relationship in my opinion,so Moky is my choice!^^
