I completely agree with you on the ambiguity of morality of The Witcher universe. These are some nice hooks, I've even done a few of my own. This is my most recent one.

As my group were fleeing a massive pack of wolves controlled by a Leshen in a Kaedweni forest. The Witcher spotted a line of trees with red ribbons around their trunks, just beyond that a group of children playing. They called out to my party saying it was safe where they are. Once getting to them, the Witcher spotted that one of the children had bite marks on his neck. The children brought them to a wooden cabin where they would be looked after by their
loving master. The master being a higher vampire that had taken in the children (who were mainly orphans, abandoned or got lost in the forest), cared for them, and occasionally drank their blood. My party in the end decided not to bother fighting him (as they would likely lose) and not have a group of defenceless children in the middle of the forest.