He looks like a mixed breed to me. I don't really know why he is acting like that to your hen. What is he doing when he attacks her??? He might be mating with her.
He will like grab her beak/ head and kind of hold her there for a second or two, and shell scream really loud! Keep in mind that my Roo doesnt have any legs. I bought him from a lady, (because she was going to... ya know...e-a-t him) We think his feet were frozen off in the winter time a lonnng time ago. He doesnt move much while trying to hold her beak with his... and then he will let her go, and they both act like nothing happened. It is the same hen that always will follow her around, and will always be the first one to come around when he yelps about something...
And I will post pics of the other three hens in the morning, I will have to take one tonight when I get home! Thank you all so much for your help!! You all are so kind!
She is his favorite and he's trying to mate with her. Since he's not dropping his wing and "courting" her it's not triggering her to submit to him, hence the fighting/screaming. Or maybe she knows he's not good daddy material? Most roos have favorites they mate with. She may also be the only one that lets him catch her!
I agree with the splash wyandotte, probably mixed as the body type doesn't look quite right. He's pretty though.