People are their memories, people that lost their memories can become completely different people, losing one memories is infact akin to a spiritual death so to speak.
I've had one or two friends in my life who suffered a severe amnesia event; in one case, what they lost was a lot of factual-informative memory; they didn't know 'who' they were, or their own name, or who any of their friends and family were, or anything about the place they lived, etc., but, they still knew how to live and operate as a person; they still knew what a book was and how to read, what a car was and how to drive (she wasn't allowed to), and for the most part, her general personality and sense of self was unaffected. It was a difficult few months because she was still absolutely the same person we all knew, in just about every way, except that she didn't remember any of us, or anything about her home, or her life. She didn't remember what her favourite foods were when asked academically, but when given options immediately gravitated to the foods we knew she would, and loved them just as he always had. Eventually, after few months, things reconnected and she got it all back, almost one day to the next, if not quite like a light switch.
The second case is a less happy one; when they woke up from the accident, they were almost entirely a complete blank slate. Core and innate behaviours remained, but little else - in particular, nothing of their sense of self or personality seemed to be intact. Over a few weeks they regained the majority of everything they needed to know and remember to function and live, but there was never any glimmer of their old self at any point, and they functionally built a brand new personality for themselves from scratch. A year later, and she was a completely different person; different taste in movies, music, food... and different taste in friends as well, as it turned out. The friend I knew never actually woke up, for all intents and purposes.
Shadowheart really seems to me to be far more in the first camp of memory loss - whether she's always been a sharite, or whether she's a brainwashed selunite, or, given Larian's desperate mary-sue syndrome with their origin characters, whether she's an avatar of both who mantled the essence of 'both' deities and thus would become an instrument of making the darkmoon heresy into truth, and had to have her knowledge of this sealed away... whatever the case, Shadowheart seems to have her underlying self and personality intact, and doesn't seem to have built it anew... So I do feel that any sudden restoration of her memories completely inverting or dramatically altering her underlying personality can only come across as poor writing. I acknowledge that I am, perhaps, biased in this.
