The breed has a lot to do with the age that they mature. For instance, Leghorns mature very early, and the heavy breeds like Giants tend to mature very late. The light breeds seem to be more aggressive, the heavy breeds are usually (but not always) more laid back.
Usually (and again, not always), roosters that are raised with each other don't fight much, since they have established their pecking order early in life. It also helps a lot if they have a lot of room to roam and stake out their own territories.
I have 3 Whitehackle Spangles (fighting game) roosters that have been fighting for about a month. They are brothers, and were raised together, but when the spring hormones kicked in, they became mortal enemies. One has been getting pretty well beat up, and I had to wash off his head, because his eyes were dried shut from blood. I put ointment on it, and wondered if he would live. The next day, he was back out fighting the other two.