I wonder if we will see an explicit re-iteration of the Yuria/Karla character in Shadow of the Erdtree.
In my mind, Sellen almost fits this category, but she seems more something unique to Elden Ring, filling the role of this world's Sorcery instructor as with others before her.
There are some interesting parallels with the Godskins and Black Flame, tying back to Dark Souls' dark pyromancies and spells from 2 and (more clearly) 3 without the associated "hex"-ness that has been more taken over by Ghostflame and the Servants of Death sorceries.
That connection also parallels with Fia, but she has her own story outside the role of instructor and spell vendor that i would associate with this trope.
I wonder if we will see a hex witch, in this way. Perhaps another follower of Godwyn, or even the ancient death practices that came before the golden order.
There is much space to be tread in the history of the Lands Between, and i fully expect the deathbirds and their outer god to play a large role in this.