I'm just randomly plopping in the convo, but: Cammy's willing to kill children because they are in her way to become King: that's just the nature of the life she was born into: a fight for the fittest to reign supreme. That's different from being a serial killer who kills for fun. Cammy doesn't get enjoyment out of killing people: she gets enjoyment out of people listening to her and giving her what she wants. She's far from a psychopath. She's just extremely bitchy and vindictive if you don't listen to her and was born into a position of power over others and no one has ever stopped her from abusing it. Yes, that means she is a pretty emotional, shitty and selfish person, but let's not act like it's on the same level of evil as someone who's a serial killer who gets hard-ons from killing people and who's entire existence hinges upon killing. Compared to the type of people where killing gives their life meaning: Cammy looks like the lesser of two evils. You legitimately just need to not get in her way and give her what she wants and you're fine. Even if you're in her way she still gives you a choice to join her just in case (RIP Owlguy-kun). For a serial killer, doesn't matter how much you plead and beg: in fact they'd probably like it more.
Yeah, the torture and kill your family thing is pretty bad, but that's actually pretty common for totalitarian governments in order to ensure submission and given she's probably been raised getting everything she's ever wanted, I'm sure she's used that threat plenty of times in order to scare someone into obeying her. If that guy would have been like "holy shit my bad, I didn't know please don't kill my family I'll listen to you from here on out," she probably would be happy that he finally came around and realized he should just obey her. Though he did break her arm so there's probably no changing her mind on that. Yes, that's bad but it's not evil for the sake of evil. It's evil for the sake of obedience.