I had two roos who were brothers. Once they reached the point where they wanted to mate, they began fighting and neither would back down. But, I have ten acres for them to range, so it wasn't constant fighting and one had his flock and the other had his in a different location. One roosted in the rafters and the other in the coop. Eventually, one was taken by a predator, but they lived in uneasy peace until that happened. Now, I have the remaining brother and his son, who is definitely the junior rooster! No fighting, only chasing from time to time, so it works out well.
As far as friendly chickens, my buff brahma is my sweetest girl! Very docile and friendly.