Elias begins seeing "glitches" in Mara. A tear running down her cheek turns into a button; the skin on her wrist unravels slightly, revealing straw and dried herbs. He finds a strange, ancient ledger hidden in the floorboards titled "Big Sister is a Witch's Work" —a blueprint for a homunculus designed to simulate familial love.
To call her a witch, in the end, is to acknowledge her power. Not to fear it, but to respect it. She brewed the coffee for you before your first job interview. She cast a glamour to make you feel beautiful on your wedding day. She hexed the ex-boyfriend who broke your heart (metaphorically, you hope). i raf you big sister is a witch work