Roosters are genetically programed to chase off any competition. Even birds that are raised together lose any kinship they might have once held. Multiple roosters can be kept in the same enclosure and often an uneasy truce will ensue. However, fights will occur. It's been my experience that a rooster that is easily cowered will not fair well with others and often serious injury or death is the outcome.
Exactly.
I was thinking permanent separation. I free range my birds all day. but I do not coop certain birds together, though they may physically share the same run, it is divided into pens during the winter when they can't get away from each other.. My marans are cooped completely separate because the fighting through the fence was quite intense. A lot of that was with the hens! Anyway, if rigging a pen with in the pen is an option then do that. But be sure to give him his own girls.