Well, after many, many hours of game play, I finally done what I thought was impossible: feed on Ulfric. While I'm using the Vampire Thirst Mod, it has nothing to do with the mod. I feed on him in the normal vampire way - while he was sleeping. He was finally not with his General. Here's how I did it: Become a vamp (duh) Join the storm cloaks Do the civil war quests After the battle of WhiteRun return late at night to report the results He was up in his room sleeping alone. If I want to go for the co-da-gra I should feed on the emperor via the Dark Brotherhood quest line. I don't think he sleeps, does he? He might if I go late at night. Hum.... Must be a real possibility. With the vampire mod I can do it - as it give me the power of seduction. However I'm a Nord Vamp, as you become a mature vamp, you can get poisoned if you drink the wrong races blood.