A group that wished to be 'ever-living' instead was cursed with 'never-dying'. Thier flesh rotted and fell fromthier bones but still they lived on. Now as skeletons they continue thier quest to remove thier curse. As skeletons they differ in that they do not need controlled or summoned. They are fully fledged NPCs with drives or ideas of thier own. Stabbing and slashing weapons would not affect them.
A group of adventurers come across a child’s body on their adventures, odd being such a remote location. Their is no detectable sign of violence to the child, nor are their any signs of life. Suddenly the child opens its eyes, looks towards the group and introduces themselves to the adventures.
If this wasn’t odd enough, the child can’t remember where they are from, only their name and age. Stranger yet, the child has a tattoo on their right shoulder of a family crest, to a family that died out over 200 years ago.