My only ever friendly D'Anver rooster, Spike, will go after Rusty for me. If he doesn't, I sometimes push him a bit by yelling, "Get him, Spike!" and he thunks him pretty good for me. Spike is really the non-violent type, though, even in the coop with the other roosters. He doesn't like it when Rusty attacks me, though.
He understands the hand that feeds him......