My Brahmas are very gentle with any other chicken I had, the roosters don't fight at all, both if they grow up in the flock or if I introduce them as adults. Until a week ago, I had 6 roosters altogether, 4 of which were Brahmas, zero problems.
All my Brahmas are friendly to humans, too, they come near me and let me pet them. When I call them for treats I see a flock of running giant chickens that seems will trample you

. Not everyone enjoys being held, but they still stay calm if I pick them up.
Anyway, I had two identical brothers (born in different clutches), which were extremely skittish, I still don't know why, I raise all the chicks the same way, maybe they were just like this.
This is Cao, the head rooster
Then there are the Bantam Cochins. The females are the most peaceful chickens I ever had, they enjoy being held and will fall asleep on your lap. As for the boys, they don't fight with other roosters as well (as they were introduced to the flock, one of the two didn't want to leave alone one grumpy broody that I was breaking

, but they're best friends now

), they run as crazy when I call them for the treats and they are hylarious, two balls of fluff that run so fast. Though, the roos don't like being held at all (they won't fight you, but they will grumble to let you know), but they are not aggressive.