Marie Fable

Edward's apprentice, an inoffensive "good girl" hiding a deep disdain for the world and everybody in it behind her sugary-sweet facade. Back home, she was secretly involved in much cult activity dedicated to the horrible cause of Bill Cipher, and her greatest goal is to summon him forth to destroy Flatland once again. She uses Edward's genius as means to learn more about the multiverse and was so convincing that he ended up taking her along in his expedition to the Nightmare Realm, mutating alongside him far past her original appearance. She lives with him, trapped in a corner of some far-off universe, and while may appear on the surface to be helping him, she has sabotaged many of his attempts at returning home and bides her time praying to Cipher in secret in the hope she will be saved. She tries to have faith, but is becoming desperate and has been going to further and further extremes in an attempt to get his attention.

(Haven't decided why she's like this yet. I feel like she has some kinda deep-rooted self-esteem problem and so she's constantly desperate for attention to the point where it overshadows everything else. Probably also a bit of a psychopath, really good at masking. Also haven't decided whether or not she wants to join Bill or is doing this as some kinda last act of rage before ending her own life. Probably the former, maybe thinks he would understand and/or validate her)