When I reported this as a bug, I was told it was intended behaviour which seemed bizarre to me as surely only people who already knew a mask could be saved would bother running rather than killing them, so I’m hoping this has been reconsidered.
I have now also gone through the Auntie Ethel Arc for the first time. It makes sense what you were told. The Vettel is like a lich and you will probably meet her again in Baldur's Gate with the so-called "Sisters of the Seeing Pearl" in one way or another.
The problem is that sometimes the masks turn neutral at the end of the fight, after Ethel is dead, and sometimes they don’t. I have not found a pattern to this. I thought it might be tied to Ethel getting in her surrender speech but that’s not it. It makes no sense to me that the behaviour isn’t consistent, and that even if they do stay hostile you can flee and come back and they are neutral.
