I think you're completely misinterpreting the character. Smith is not at all a serial killer type. It's much worse. He's a fairly normal fellow, who under OTL circumstances would be a regular world war II verteran and a loving (though rather stern) family man. But in this ATL reality? He becomes something else entirely. Assuming that he is inherently this monster completely misses the point, which is that he represents the monstrous potential in all of us. Under the 'right' circumstances, people who would be basically decent in OTL will instead give in to their darkest impulses-- because it benefits them, because it keeps their family safe and affluent... because it's just so god-damn easy. Smith is (metaphorically) the embodiment of the idea "if Hitler had won, we'd all be speaking German". Being a Nazi would just be normal, being anything else would be a deviation. One that may well get you killed, or at least destroys all possibility of social advancement, job promotion etc. -- Whereas being a competent military man (a traith the Nazis value), of pure Aryan stock, gives you the exact right position to advance under the "New Order". Just as long as you're willing to shut down your conscience and get started on gassing all blacks, jews, homosexuals etc. etc. The point being made is that the vast majority of humans would look the other way, just as the vast majority of Germans (not Nazis at all) looked the other way. And men like Smith -- though by no means destined to be evil psychopaths, but career military men, who've seen extensive combat and are already desinsitsed to brutal slaughter -- well, it's almost inevatible that a good number of them become Nazi butchers in a world where Hitler conquers the world. And in OTL, he'd just be your polite neighbour John, who hosts the annual barbeque and takes the lads fishing on the weekend. He'd likely be horrified by the Nazi version of himself, because -- like all of us living in a comfortable, 'normal' world -- he'll have convinced himself that he'd never do such things. But he would. And so would most other people.