I am of the opinion that the Dark Brotherhood secretly still serve Mephala, whether or not they are aware of it. The Morag Tong certainly follow her teachings, and their history is strongly tied to that of the Brotherhood. I don't believe Sithis actually has any sort of awareness. It is an anti-force, not a deity. If something speaks to the Listeners through the Lucky old Lady, it's not Sithis, but Mephala.
It is easily possible that Mephala is still in charge of the DB, or that the night mother herself is a manifestation of Mephala, it is certainly not out of charecter for Mephala, who seems to greatly enjoy screwing with people. But the fact is that sithis could easily have some sort of awareness, in alot of myths and legends the world it's self is considered a living sentient creature. We could say that the conciousness of sithis is so complex and difficult it is out of our scope of understanding. But think about this, if you leave a big enough rock with the right stuff on it in the right place conciousness happens on it's own. Sithis could be the collective conciousness of an entire universe of pure
force.
Speaking of such, we can no call sithis an anti force, like i have said before to many people assume that sithis is a bad thing, even if it is not sentient, it is some evil force. But the truth is Sithis is the
Orginal Force I mean if sithis was some anti force what would the original force be, we would only have one option and that's anuiel, and anuil is the embodyment of stasis, and the oppossite of chaos, meaning that he could contain no energy at all beacue energy causes change, and within anuiel it is quite clear nothing ever changes. So for any one who did not entierly understand the monomyth, in the begining there were only two things Anuiel, the embodyment of stasis, and Sithis the embodyment of change, there was no good, no evil, no happy no sad, no is, no is not just change and stasis, and everthing happened when sithis changed anuiel, and that place is nirn.
But deeper in, I'm truly now wondering if/how Sithis will affect TES V. >_>
well, we know TES V is gunna be big, and the games have gotten into progressivly bigger stuff, i think mabe that in TES we may get down to the wire, and get to know the secrets Nirn is made of. I think those big two original forces may play a boh part in the story, but who knows hehe, it's gunna be a few years before we see TES V anyways.