User blog comment:G0LD3NF1RE/Skyrim Dawnguard DLC/@comment-3251634-20120503152108/@comment-30303790-20120503161741

Wait, what about the Shivering Isles made forced the player to be evil? Daedric Prince, yes, but not completely evil by any stretch. It's not like it made you Sauron and you had to go around hacking up hobbits and puppies in order to complete the story arch. I can only think of one instance in the DLC that forced you to be "evil" and even then it only the circumstances make you look evil.

And what about the Knights of the Nine? That DLC required the player to be virtuous. You have to go on a pilgrimage to purify yourself, and then you must go on to complete a series of quests to retrive the weapons and armor, many of which require you to do selfless things. On top of all that, if you try to be an evil bastard you get stripped of your ability to use the items until you re-purify yourself. Oh and the whole point of the DLC was to stop an ancient evil.

I think you might need to go replay the DLC, and if you're talking about all Bethesda games you probably need to go play through the F3 add on as well.