Uhh..

I think the little brother is the boss. But I don't think they're real brothers. He probably just call him brother by chance by being together. I'm just guessing from the hint the story show. The brother probably forgot what the fox (mc) look like due to his sickness when he was in the hospital from what I see in the story flashbacks. And since fox is know for scamming, the brother probably didn't know that was mc that he was looking for.