RYTX i agree, like Visser 1 noticed in book 30, they mostly didn't kill human controllers if they could avoid it. Cassie was one of the most torn up when they ever did have to kill a human-controller due to the fact that the human was held hostage by the enemy,with no way to separate them. When it comes down to kill or be killed though, which it was most of the time, the choice was clear.