If you're looking to prepare for the new content, you can find our guide here, but the development team is now giving us fresh lore for some of the expansion's major characters.
As per a blog post, Fennorian is a Vampire Scholar of House Ravenwatch. Fennorian appears in the Unhallowed Grave dungeon, but his Vampiric affliction brings him into the main story of the Dark Heart of Skyrim Quest that's set to run for a year.
According to the post, Fennorian is a studious character that might be tougher than he seems – and potentially a little on the eccentric side.
We'll find out more when we meet him on May 26 for PC and Mac players, or June 9 for Xbox One and PS4.