We've honestly never noticed any aggression. If anything, it's one of the Rhode Islands who we might consider alpha. She's the one who gets all the snacks and pushes everyone out of the way when we enter the run to be first in line...but still never pecks anyone...and never noticed any blood or red spots.
To be safe, we're going to add a few perches and another flock block to entertain them. We have also been considering a higher protein diet. They get a LOT of table scraps, mostly greens, and we give them all the garden waste. I'm worried with all the greens they eat and only a 16% layer formula, they may not be getting enough protein?