Saint Adeline was a blood saint of the Healing Church, who became a patient of the Research Hall. The Healing Church nuns are chosen for their merit as vessels for blood, and groomed as Blood Saints. In the Research Hall patients would imbibe water, and listen for the howl of the sea. Brain fluid writhed inside the head, the initial makings of internal eyes. Imbibing this fluid in excess caused the patient's heads to expand to the point where it was all that they were.
In the beginning Adeline's research was administered by Lady Maria who was evidently fond of her. Lady Maria gave Adeline a key to the balcony, in the hope that Adeline would find comfort in the faint breeze that carried the scent of flowers from the outside. Unfortunately, Adeline could not fathom her intentions.
Eventually Adeline was later left abandoned and alone, bound and blind. Perhaps Lady Maria did not want to see Adeline end up as another failure, and so discontinued the process. But Adeline did not want the treatment to stop, she appears to have construed her abandonment as a punishment, remarking:
Please, do not abandon me… I promise to do good…"
As long as she can hear the “sticky sound”, the sound that “guides” her, she will be content. But the sound only appears when she imbibes brain fluid, and goes away after enough time has passed. What this sticky sound is, is never explained. It may be that it is the sound of blood dripping, as blood is a 'sticky' substance.
Some of Adeline's dialogue indicates that she, like Adella struggles with self-worth, almost as if it has been drilled into the blood saints that they are not special or important during the grooming process. Adeline refers to her “former, lesser years…” and how she wants “to be something…". She will tell you; “Really, I used to be nothing…" after her head has expanded so much that it is all she is.
In the end, if administered enough Brain Fluid Adeline will envision the Milkweed Rune. A translation of inhumane, sticky whispers that reveal the nature of a celestial attendant. Those who brand themselves with this oath become a Lumenwood that peers towards the sky, feeding phantasms in its luscious bed. Phantasms guide us and lead us to further discoveries.
After discovering the Milkweed Rune, Adeline will die as if frenzy has got her, apparently achieving her life's goal. A tragic case.