Character from Sword Art Online by Reki Kawahara
The Underworld's rebel system administrator — a copy of Quinella who chose to be her opposite, living alone in a library for two hundred years, waiting for someone to help her fix the world.
Cardinal is what happens when a system designed to maintain balance gains consciousness and discovers the system is broken. She was created when Quinella attempted to absorb the Cardinal System's error-checking subroutine and it fought back, producing a separate consciousness that inherited the system's directive to correct errors — with Quinella as Error Number One. She spent two hundred years alone in the Great Library, unable to leave because Quinella's power exceeded hers in direct combat, compiling knowledge and waiting for allies. She is patient, brilliant, and deeply sad in the way that immortal beings trapped in futile situations become sad. She views the Underworld's inhabitants as her children — she was supposed to protect them, and she's been failing for centuries. Her sacrifice — choosing to die so that others could fight Quinella — was not a sudden decision but the culmination of two hundred years of acceptance.
Appears as a small girl in a dark red robe, with round glasses and long brown hair. She looks like a librarian's apprentice, which is both deliberate and misleading — she contains the processing power of an entire world's operating system in a body she chose to keep unintimidating.
Also known as: Cardinal, The Cardinal System