Fiona was a violent "serial killer" Norn, originally hatched by 264redjack in a C3/DS world. He originally posted Fiona in a Gameware Forums thread (includes download) saying that she had killed 3 other Norns in under 15 minutes. Independent testing by Officer 1BDI and others confirmed her violent nature. Various theories were proposed but none were conclusive.
Fiona and Quilla were used in the creation of the Hunter Norns.