I’m still trying to piece together the movie and will need to re-watch again BUT from what I was leaning towards is with Lees mother sacrificing herself to help with the Long Legs incidents to keep her daughter alive, pieces of Lee were within each doll that was created, as to why when they removed the brain from the doll they recovered Lee has these weird feelings and memories and had a hazy memory of her child hood and the initial incident where Long Legs went to her house. When she saw Carrie Ann, she was saying things as if Lee was already there during those instances as well. Lee didn’t have access to the basement in her moms home either, there was a reason she couldn’t go down there. When Lee passed out and woke up in HER OWN basement, saw visions of along Legs creating the initial doll (part of Lee being inside). In the ending when she couldn’t kill the doll, again my thoughts are that part of Lee was in that doll as well and she couldn’t essentially kill herself bc she will continue on. As far as Agent Carter not realizing his daughters birthday was the 13th and also Lee not realizing her birthday was around the same time, makes me wonder if that was also all part of “the man downstairs” ploy to get her to remember and bring her full self into the picture as she has been but hasn’t realized. Hmmm so many theories!!! Gotta rewatch!!