NPC Conversations would need to be limited to which NPC you speak for, Many NPC's have established stories, personalities and feelings that the "higher up's" have worked hard on.
Speaking for Barovian Peasant #435 would be fine (as long as its cannon)
But speaking on behalf of named Charaters like Lizuca or Horitiu, not cool.
Making up NPC's for your bio and speaking for them
Cool Beans.