If you are not caught up, you may want to go back and read the previous adventure or this one is unlikely to make any sense. Although, since Vanir "mildly retconned", it may not be entirely necessary to read the previous post.
I often like to throw in unique NPC’s who are the only member of their race / species. For instance, in a campaign that I was running about 12 or so years ago, I created a half-red dragon half-black dragon hatchling that was going to play a role in the entire campaign. You can download a PDF of the first adventure in the campaign (the only one I actually ran) on the resources page.