I've heard of mean roos, had one myself, a little banty. He would attack me at dusk (maybe he had eyesight problems?) but the big Cockerel, "Sargent Pepper" always came over and told the little guy off. Sarge is a bit stand-offish, but protects his girls and "ME" too! Love that boy! 
I have no idea why he's such a good boy - he was a naturally raised chicken, his momma trained them all very well. He has had little human handling, but he's very respectful of humans, and he's a gentleman to his girls. 
I won't have a mean roo - if he's mean to me, he may be mean to them. I got rid of the "rapist" bird 2 weeks ago. He would hide behind the tractor and jump out on hens as they strolled by. Poor Sarge had such a time trying to be everywhere protecting them.
Kathy - waiting for the hatch - 1 day to go!