Rosalie Hamburgang

The true Rosalie survives only as a preserved, mummy-like corpse concealed within the mansion's West Wing, a grotesque shape that seems to hold some silent, unknown soul. Amy, the orphan who stands in for her, was selected because she looked almost identical to the family's lost daughter.

As the family's only child, the original Rosalie was thoroughly doted upon by her parents, the household staff, and Jude alike. Her replacement, Amy, comes across as a lively and inquisitive girl who does not shy from the truth, openly revealing the family's secret to Edward and Alphonse. When the brothers ask why she keeps up the pretense rather than returning to the orphanage, she explains that she is happy where she is; her circumstances improved once she took on the Rosalie name, and her new family treats her with real kindness.

After Rosalie died young from an unexplained cause, the family alchemist Jude swore to restore her through human transmutation. The attempt failed and cost him his eyesight. To spare him further anguish, Rosalie's father told him the transmutation had worked and commanded that the truth stay buried, while the body was hidden away in the West Wing. Needing someone to pose as the girl so that Jude would never learn otherwise, the Hamburgangs took in Amy from a nearby orphanage, a child who happened to look nearly identical to their daughter. Edward and Alphonse uncover the deception when they visit the estate to investigate Jude's supposed success and are shown the disturbing living body left behind by the failed experiment.

Commentators have suggested the tale may draw inspiration from Rosalia Lombardo, one of history's best-preserved mummies, whose story shares the similar name, the brownish hair, the status as an only child of a rich family, an early death, and preservation by a grieving father.