Sibylla Draconis is the youngest member of the Draconis Family. You need to kill her and her family to complete the quest handed to you in the Dark Brotherhood by Lucien Lachance to receive 500 gold.

As noted by her mother Perennia in the shopping list she gives you (or you take from Perennia's corpse), Sibylla is a 'feral' woman. Indeed she lives amongst wolves, bears and mountain lions in Muck Valley Cavern and immediately becomes hostile when she sees the player. She either hangs out near the entrance of her cave or near her bedroll/fire pit area. She wears the Huntsman vest and Huntsman loincloth and only fights hand-to-hand. Her mother pays you to buy her a nice, warm blanket.