My "mean" cockerel started out sweet, but his personality slowly changed until he became incredibly aggressive towards my husband and son. It was a shock to all of us when he suddenly went on the attack. He's shown a small amount of aggression towards me, but nothing too bad, but he HATES my guys, and neither my husband nor my son had ever done anything to illicit such a profoundly angry response from him. I know this rooster is more familiar with me than with them since I'm the one who handles and manages all of the chickens on a routine basis, but my guys interacted regularly with him as he matured to maintain familiarity. None of the other Turken cockerels are a problem, but this one is, perhaps because he's the dominant.
My husband especially has been incredibly supportive of my new-found chicken obsession. The least I can do in lieu of that support is remove one aggressive cockerel that seems to see my guy as a sparring partner. He'd really like to be able to walk out into our yard to mingle with the chickens without having to use me as a human shield.