Daniella, being the castle's maid, cooks and does the household work around Belli Castle. She also tends her own garden of mandragora, which are screaming human-like plants that either scream or use their poisonous leaves as a defense mechanism. Daniella's movements are marionette-like and her behavior is unnerving. She wears a long, blue-green maid dress with a stylized Caduceus symbol on her shoulder. In Hard Mode, Daniella's dress is a deep red color.

Daniella is eventually revealed to be a homunculus, which is an artificial man-made human. It appears that Daniella was created by Lorenzo much longer before the events of the game came to Fiona realizing Daniella wanted to be the perfect woman. Since she is a maid, she is serving Lorenzo for his cleaning and cooking tasks that he is unable to do himself due to being confined in a wheelchair.

Initially, Daniella seems unemotional and apathetic, but to Fiona Belli's despair, she notices that she's prone to erratic mood swings, split personalities, and maniacal laughter. Daniella might have a split personality disorder, alternating between intentions of murder to ignoring Fiona altogether in order to clean parts of the mansion. Despite her beauty, Daniella hates looking at herself in the mirror and will shriek at the sight of her reflection; her reflection reminds her that she is an imperfect, artificial creation that cannot taste, feel pain, have sexual intercourse, have emotion, or bear children, which means she isn't perfect and she gets angry at herself, thus, screaming at the mirror before breaking it.

Daniella chases after Fiona out of jealousy that Fiona can have children, experience pain, pleasure and human emotion as she possesses the Azoth, which Daniella believes will make herself human, and "complete". With no knowledge of alchemy, Daniella does not know how to extract Fiona's Azoth and she believes that if Fiona is killed, she can simply take it from her dead corpse (after ripping Fiona's uterus).