Vierne is a human with important information in Aralon: Sword and Shadow HD. Darius sends players to her as part of the main quest because she knows about the Temple of Azra and the Scepter of Hammara. She also knows an important crafting recipe, a soothing balm, that players will need in order to get the dragon Sunclaw to work with them.
Many players seem to get caught up in getting Vierne to give them the soothing balm recipe. She will not give the recipe out until the player has talked to Sunclaw and he or she has received the "Soothing Balm" quest from the dragon. Thus, the first time players speak to her, she will not give the recipe or if the player does not take the soothing balm quest from Sunclaw, she will not give it to him or her.
Vierne is considered a friendly target so if she is killed by the player, it will not affect his or her legal status. Players can also take the loot in her chest without negative consequence.