Ooh, speaking of which, I have some more work to do. My original vision for the Witch had her fighting against a kingdom that was mind-controlled by its monarch through face-activated magic, which required her to wear a mask at all times. To the mind-controlled observers, anyone who dons a mask appears to turn into a wraith, cementing their perception of her villainy.
What if, in this RP, the mask puts monsters more at ease around her? Maybe humans have a horrible reputation (because of course they do), and she wears a mask to communicate that she's not like other humans, perhaps even to communicate alliance or something.
Which leads me to a question: why might she come to defend the monsters? Perhaps because she sees herself in them?...
I have work to do on this...