I just joined the Dark Brotherhood on my current character, and I've noticed it seems I can't hide from any of them. No matter what I do, the eye stays always open when one of them is in the room. Even if I'm alone in the room with just one, and I'm sneaking behind them, I'm detected. Even when I use an Invisibility spell or potion, I'm still detected.
Does the Dark Brotherhood have magic eyes in the back of their heads or something?
Note: This is with a level 81 character. The only sneak-enhancing equipment in use (if any) was a pair of boots I'd enchanted myself. Can't remember the boost level.