Vampires: In Skyrim, you can contract vampirism but meeting a vampire lord means you can THEN be "transformed" into his particular strain... almost as if the initial strain you contract merely sets the stage for what you can ultimately become. Vampirism is not completely static in Skyrim. So I can totally see Vet level quests that, depending upon your choices, would set you up to serve one of a handful of different, very powerful, vampires and successfully completing their missions would then result in them "blessing" you with their particular, stronger (edit to add: when I say "stronger" all I actually mean is "more choices" not abilities that are OP), strain of vampirism. It wouldn't really be stronger in terms of game mechanics but would give you new additions to your already existing vampire skill line that you could then choose to replace other abilities with. A "vampire lord" Ultimate akin to Skyrim would be pretty sweet though!

For quest rewards I think they should vary depending upon which vampire lord you choose to serve. I realllllly would hope that one of them would be a Cyrodilic vampire that could reward you with an item that would, when slotted, allow you to look like a normal human/mer (as in whatever your character looked like BEFORE becoming a vampire) up until you hit Stage 4.

What other strains of vampirism would you like to see represented and what would you like to see as rewards for completing their quests?

What other vampire abilities would you like to see added to the vampire skill line?

What kind of story arcs would intrigue you and keep you engaged?