From Wiki http://elderscrolls.wikia.com/wiki/Daedric_Princes of domination and enslavement of mortals. His only desire is to harvest the souls of mortals and to bring mortals souls within his sway by spreading seeds of strife and discord in the mortal realms. He holds much importance in http://elderscrolls.wikia.com/wiki/Morrowind, where he is seen as the archenemy of http://elderscrolls.wikia.com/wiki/Boethiah, the Daedric Prince of Plots.

Maybe the parts that I've highlighted have something to do with it

Maybe...transform at will for as long as you want...?

I hope for first person vampires.

There is a power mentioned that drains souls...


I want proof instead of rumors... any site can guess anything on DLC and say it came from a good source but how many have been purely keen and percise

Im starting to really think that the Dawnguards will be based around lycanthropy. No other reason to have the skill tree.