Lore theory about the Formless Mother. Elden Ring spoilers specifically relating to Mohg and Rykard below.
I think the Formless Mother might be Daedicar, or at least related to her in some way.
“Disturbing likeness of a woman whose skin was flayed.
She smiles with a serene tenderness.
It is said that this woman, named Daedicar, indulged in every form of adultery and wicked pleasure imaginable, giving birth to a myriad of grotesque children”
Yes, she comes up in the context of Rya’s questline and is associated with interspecies sex/forbidden acts. But I think it’s significant that her talisman doesn’t like, gain enemy attention the way Shabriri’s does. Instead it increases damage taken, and the description on it seems to indicate masochism. And… who likes to be wounded? The Formless mother.
Further, it describes Daedicar’s children as grotesque… and the Formless Mother is willing to take on socially ostracised or enslaved races such as Omens, albinaurics, and Tarnished (presumably) as her worshippers. I wouldn’t be surprised if she also took in misbegotten, but I can’t back that with anything from the game. But… Mohg, specifically, took on the Formless Mother as his new mother, and is also associated with sex and violation of taboos, akin to Rykard. Both of them also have lieutenants who seem sincerely dedicated and loyal to them — White Mask Varre and Lady Tanith. Who also wears a white mask. The parallels aren’t subtle. (I’ve seen something about Rykard having a male consort in earlier concepts of the game but I can’t speak to the validity of that). I think Daedicar might actually be the Formless Mother, and the parallels between Mohg and Rykard were supposed to tip us off.
(I realised this while discussing Mohg with someone and ran off to write an essay.) I’ll probably add to this later. I’m sleepy now, but I wanted to get the thoughts out. It’s interesting.