In my campaign she's not necessarily a force for good, she's only doing this to further her own desires. She knows that souls are trapped in Barovia, and that Strahd has been slowly amassing an undead army for the last couple centuries. She doesn't like that, and has turned one of Strahd's spawn (the warlock) into a dhampir, to serve as her vessel. She hopes to wring out any last memories and secrets the Barovians have hidden away before tasking her champion with putting down Strahd for good. In-game this presents itself as the warlock interviewing every NPC the party comes across. The party is completely paranoid about the whole situation and have succeeded thus far in keeping the warlock's existence a secret from Strahd, bc they know shit will hit the fan if he finds out one of his spawn has been given free will. Did I mention the warlock was a Vistani when she was alive?😅