Back in the late 70's (?) there was a mass killing of elephants in a specific area. Especially the largest, most mature bulls were killed off. As a result a lot of young bull calves grew up unrestrained. They started exhibiting some really aberrant behaviors. Killing rhinos, destroying fences and crops, damaging villages... you get the idea. It caused quite a stir in the local area and everybody was puzzled by the sudden and alarming increase in violence. Finally someone suggested that the bulls had grown up without discipline from older bulls... and they imported some old bulls from other areas. The old bulls took charge and they put the young bulls in their place. Maybe you need a bigger, stronger, calmer bull to show yours what's what...
I watched a documentary about that a few years ago. It started out showing, in black & white, video of the government gathering up a huge herd of elephant, in an area where they were starvinmg to death. They machined gun down al the mature elephants, and caught up al the young babies and sent them to recue facilities. But there were many "teen aged" elephants, that were big enough to forage for themselves, and they ran in juvenile groups. And like you said, they grew up to be outlaws..juivenile delinquents. And the males took to killing off rhinos in that park. And yes, when someone suggested they import 3 mature bulls, it wasn't too very long til they taught the young uns some manners.
There is a similar situations with young stallions. In the wild they will be run out of the herd, and they live in bachelor groups til they get to be about 5, when they then venture out to challenge a herd stallion for his herd of mares. They have spent their 3 and 4 yr old years, learning to fight developing a pecking order, etc. and learning "horse etiquette". A typical colt is weaned at 6 mos in domestication, and is taught and trained by humans , often kept alone, in a stall, etc. Some of these , when they get about 3 years old, become 10' tall and bullet proof. They want to fight and pick on other horses, and nothing much a trainer can do about that. So, what you do, is put that 3 yr old in the pasture with a herd of mature bred mares. It doesn't take too long, til they kick Junior down to the bottom of the pecking order, and he loses that "
I am a bad-ass" attitude, and becomes socialized into the horse culture.
That is a very good suggestion you had...about putting in a "boss bull" with him.