All my different breeds as pullets were sweet and non-combative and were free-range in the yard. Some went as old as 3-years before starting to display assertive or aggressive behaviors. My dual-purpose or egg-layer breeds - White Leghorn, Buff Leghorn, and Cuckoo Marans - became so insanely aggressive, vicious, or cannibalistic toward the gentler breeds (Silkies, Ameraucana, Breda) that we no longer keep the heavier or assertive breeds and re-homed the bullies to an egg-seller's flock of dual purpose or egg-layer breeds. It puzzled us because our White Leghorn was a nice gentle alpha leader for 3 years and then one day went bonkers on her flockmates. The Buff Leghorn went cannibalistic on her flockmates at one year, and the Marans viciously attacked a Silkie pullet - not good to have 7-lb bullies around 2-lb bantams we learned the hard way. We caught the offensive bullies before any serious injuries and I no longer tolerate the slightest offensive behavior in a chicken. I wouldn't have minded putting some offenders in a stew pot but my tender DH re-homed the offenders into egg-layer flocks where they no longer could bully timid or gentle birds. After cycling through 13 birds in 5 years we are finally down to our gentle 4 birds all 5-lb-or-under. We tried an odd number of 3 birds or 5 birds but found the 4-bird backyard of gentles the best for us and they've been hanging around together in pairs. When we had 3 or 5 birds there was always an odd-man-out for pairing.
THIS PARTRIDGE SILKIE AND BLUE WHEATEN AMERAUCANA ARE OUR GENTLEST BIRDS AND SEEM TO HANG AROUND EACH OTHER.
WHILE THE PARTRIDGE SILKIE SECLUDES HERSELF IN THE DOGHOUSE, THE ACTIVE BLUE BREDA AND SPUNKY BLACK SILKIE HANG OUT TOGETHER BUSILY FORAGING AND STEALING TIDBITS FROM EACH OTHER LIKE IT'S A GAME!