Before heading to Dimhollow with my new character, I decided to pick up some Shouts, including the two words for Marked For Death that are not inside the Dark Brotherhood Sanctuary. Imagine my surprise when finding the words—Kill and Leech—triggered the learning of these words for Drain Vitality as well, even though that Shout's words should be Health, Stamina, and Magicka. Kill and Leech show up under both Marked For Death and Drain Vitality, and when I unlock a word in either Shout, it unlocks it for the other Shout as well. As far as I can tell, Drain Vitality does work with the wrong words. However, since both it and Marked For Death drain the target's health, I can't be sure that when I'm using Drain Vitality, it is Drain Vitality and not a copy of Marked For Death. The new Shout animation occurs, but there is no vocal Shout performed. I haven't gotten the real word for Drain Vitality from Dimhollow yet; I'll update when I do. For now I would suggest everyone stay away from the Marked For Death words if you do want to get all three proper Drain Vitality words.