Of course she isn't evil. She takes very good care of her subordinates.
Absolutely false. For one, as noted above, she freely makes sure they die, if they disappoint her enough. Second, ANY truly competent administrator (sociopath or no) will treat their staff quite well, as long as
they follow the rules of both the organization and her own "special set".
As I said above, Tanya is a nearly-perfect example of "Lawful Evil" from AD&D, while you are thinking more of "Neutral Evil", or even "Chaotic Evil". Remember, just because you're evil does NOT mean:
- You can't have (and even be loyal to) friends.
- You don't keep your word. Few are going to be willing to deal with you, if you have a reputation as a betrayer.
- You are stupid (murdering your staff is NOT the way to get superior performance).
- You break the law. In fact, EXTREME over-adherence to the law can be amazingly evil; remember the Nuremburg trials, where the Nazis tried to claim they did everything due to orders, so it wasn't their fault? There ya go.
- And so on.
In fact, sociopaths IRL often end up in similar situations to Tanya; a hugely disproportionate percentage of politicians, CEOs, middle managers, and cops are sociopaths, where they can indulge their "itch" in a manner at least mostly endorsed by society.