[JoeyP]

Hmm..... Knowing hiw my guys ask for play
I think you might be misjudgingbthe behavior from you dog

I think you said that he runs in circles around your brother and barks at him
It sounds more to me that he is getting excited and is demanding play

Does the dog shrnk away from him if your brother goes to pet him?
Or does he wag his tail?

Does you brother play with your dog?
If the answer is yes then its not a fear based thing
He just wants to play

My guys will growl and bark at me until I give in or have enough of their antics when they want to play