I have been reading the forums and I have noticed post's saying that the whole night mother thing and the dark broterhood being made is a hoax being done by the deadra prince mephala that the dark brotherhood is actually serving her instead of the sithis. Is this true? or is it only a theory? I am quite interested since this could add a new dimension for roleplaying my characters. Does anyone know more about this?

I am looking up information about Mephala and the things that the DB does kinda seems like her kind of thing.

I've heard the same thing, and would like to know as well. It's sort of been bugging me. I wonder if my characters have been duped into believing in Sithis and the Night Mother.

It's speculation though some things point to it but unless i hear words from Bethesda i will be skeptical.

Well Sithis is an underlying force of the universe, it's not capable of caring if it's worshipped or not. As for the Night Mother, well the corpse is real, but whether the one who is speaking is her or Mephala is another question...

This.

Well I could see Mephala speaking through the night mother but it could all be speculation as people say in this topic.

On the other hand, in Morrowind Mephala clearly directed the Morag Tong. The Morag Tong and the Dark Brotherhood being severe enemies to each other doesn't really help the theory. But maybe Mephala simply likes causing chaos and setting up her own guilds against each other ...

Well going by her description she would do stuff like that I mean here is her description on the wiki.

Mephala whose sphere is obscured to mortals; known by the names Webspinner, Spinner, and Spider; whose only consistent theme seems to be interference in the affairs of mortals for her amusemant.

I mean her sword in skyrim gets stronger when you kill people who trust you and are friends with, you hell the sword gets to full power if you kill your spouse.