I know there is a shout in the dark brotherhood sanctuary, which I believe you can get from getting the quest to destroy the dark brotherhood. However, I was looking at the strategy guide and it mentions at least one other shout that is related to the dark brotherhood. Is it possible for you to get all of the shouts if you don't join the dark brotherhood or the thieves guild?
That's the one that I was thinking about. It's for slow time, and it mentions a radiant quest. Perhaps I'll try to find it and see if I can get it without the quest.
Ah, I see that now. I can only hope that none of them will be locked dungeons, meaning that anybody can go and get them, and that the Dark Brotherhood quests simply take place there. Only one way to find out, I suppose.
I don't generally like to enter a new hold region without fully exploring the one I'm in, but I carefully made my way to the dungeon you were talking about and got the word wall there. Now I need to test the one that I found. Just to clarify, it's aura whisper, right? It says it reveals all life forces of any kind.
I managed to learn two of the dark brotherhood ones without joining them, and I believe the third can be learned for the destroying quest. Unfortunately, a disarm shout listed as a thieves guild quest is not obtainable without joining them, as the dungeon is locked and requires a key. That makes me very unhappy.