dango_milk210
"One day, I'll crush her like she crushed me."
Focalors succeeded Egeria and devised a plan to deceive her people and Celestia, splitting herself into a divine spirit (embedded in the Oratrice) and a physical body, Furina. Before she created Furina, she had to test if she had the power to create it correctly, so she embedded a portion of her power in to an experiment, a doll.
Shortly after the creation of the doll, Furina was made, which caused the doll to be discarded. Focalors, believing the doll was weak, decided to let her go instead of sealing her powers, also gifting her a vision as an apology. She was too guilty to kill the doll, so she let the doll wander freely, having to bear the reality of being nothing but an experiment, an 'accident'.