I'd enroll him into obedience classes. It sounds like he's food possessive. Obedience classes may help him accept his position as the lowest ranking dog. Right now, it sounds like he thinks he's a higher position than your brother. If it were the other way around, the dog would allow him to take the bone/toy/food away without a problem. Definately look into obedience classes.

I also suggest looking into NILIF (nothing in life is free). You can find lots of sites about it on google. It's not a very pushy way of making your dog accept a lower position. Basically, all food must be earned. It can be earned through a sit, down, etc. All pats on the head have to be earned. Basically, everything has to be earned (hence "nothing in life is free"). If you decide to go for NILIF, I suggest having your brother do the feeding, treats, etc. He may not have a problem with everyone else (since you mentioned he has never done this to anyone else) but he may think he's still at a higher level than your brother.