Quinella

Quinella (クィネラ) is the actual ruler of the Underworld as the highest minister of the Axiom Church.

Background
She was born 350 years before Kirito enters Underworld for the second time. She was the product of a political marriage between strong noble families at that time, her father was the lord in charge of the, at that point, Town of Centoria, and was the one who gave the Sacred Tasks. To maintain power in the family he created and bestowed upon her a new Sacred Task: Sacred Arts Research.

History
She discovered new Sacred Arts that the other Underworld Residents hadn't known. By studying the meanings of the words used in the commands, she was able to form the first offensive command, the «Thermal Arrow» and with it, she discovered that killing any other living being, will increase the person's stats, so she sneaked out of home every night to hunt nearby animals and rose her stats at an incredible rate.

Taking advantage of her knowledge, she made people believe that she was gifted by gods, and took the opportunity to start creating the Central Cathedral, and with it, the Axiom Church. She created the Feudal System in Underworld by making the lords into nobles and thus, creating a structure to control the entire Underworld. The restriction imposed by the Axiom Church on lowering the life stats of living beings was created by Quinella to prevent other humans from grinding their authority levels.

As her power grew, so did the tower in the Cathedral. From a certain point of time, she no longer showed herself to those of the world and immersed herself purely in the analysis of the Sacred Arts to transcend the ultimate limit set upon her, «Life». She became anxious because, despite all her power, her life continued to drop and there was nothing she could do about it, until one day, when she was on the brink of death, she managed to find a command that allowed her to see the list of all commands accessible in Underworld, at the bottom of which was one that raised her System Control Authority level to the maximum and granted herself the authorities that were reserved only for the Cardinal System, including terrain manipulation, item generation and even the manipulation of the durability of dynamic units, including humans.

Quinella immediately used her new powers to completely restore her own Life, halt its natural degeneration and recovered her former appearance from her years as a youth. However, Quinella was not yet satisfied. She could not permit the existence of one that had an authority level equal to hers - the Cardinal System. While recklessly trying to decipher the complex syntax of supervisor-level commands via a reference list created for RATH employees, she devised an extensive complicated command in hopes of stealing the powers of the Cardinal System. However, a single yet enormous error with reciting the command led to her burning the core principles of the Cardinal System onto her own Fluctlight.

Awakening only after an entire day of sleep after reciting the command, Quinella didn't age, didn't need to eat or drink, but she inherited a single desire from the Cardinal System - to regulate the world, but she went further than the Cardinal System in regulating the world. She desired to keep the Human World the same for eternity, but to achieve this goal, she needed to take control of the most unpredictable factor of the world - the residents.

Quinella took various actions to restrain the lives of the residents. Firstly, she proclaimed a single edict to split the Human World into four empires and made the four great nobles of the age into the emperors of the new empires. She then used her supervisor powers to instantly create the «Immortal Wall» that separated the empires, thus creating a physical barrier that restricted the movement of the residents. She also created various other barriers i the more remote regions of the Human World where pioneers had founded new villages. Among these barriers was the Gigas Cedar. Even psychological barriers like the «Bells of Time Telling», which could only be heard within a certain range within a town or village, among many others were used.

However, Quinella actually inherited 2 instructions from the Cardinal System. While the main process was in charge of regulating the world, a separate sub-process was in charge of performing error corrections on the main process. The main process was in control of Quinella's body for most of the time, however, whenever Quinella's consciousness slackened, the sub-process was able to float up to the surface of the thought process. The sub-process deemed the main process, Quinella, to be conducting a great error, as the Cardinal System was not supposed to directly affect humans. Therefore, she tried to cause Quinella's death multiple times, but failed due to Quinella reassuming control of her body.

Having realized that the sub-process has become a threat to her, Quinella sought for away to keep it locked in within herself. Noticing the the sub-process could only take control of her body during times of emotional distress, Quinella decided to freeze her emotions to stay in control of her body at all times. By now, she had been abducting Underworld residents who questioned the Taboo Index and the Axiom Church and using these captives as guinea pigs for experimenting with Fluctlight altering commands, called the «Synthesis Ritual». Through these inhumane experiments, she was able to test which part of the Fluctlight should be altered to change a person's memory, thought patterns, emotions etc. Having tested this ritual long enough, Quinella applied the ritual on herself and was successful in freezing most of the emotions that were the cause of her unrest: fear, anger etc.

Approaching 150 years of age, Quinella noticed an anomaly within herself. Various incidents, from briefly losing her consciousness even outside of sleep to not being able to recall recent memories and even having trouble recalling the Sacred Art commands that she should have memorized perfectly, had been happening recurrently to her. Upon examining her own Fluctlight, Quinella was shocked to find out that the memory capacity of her Fluctlight had reached its limit without her knowledge. Because of this newly found limit on her existence which could not be controlled like Life, Quinella sought for a way to overcome it. That's when she devised a devious scheme for overcoming the memory limit on her Fluctlight - hijacking the Fluctlight of another person who had plenty of memory capacity to spare and using the said victim's Fluctlight to store a backup of her compressed memories, before manipulating her own memories to free up more space on her Fluctlight.

At the time, a 10 year old nun had been studying Sacred Arts on the lower levels of the Central Cathedral due to her above average system access authority. Quinella selected this nun to be the vessel for her backup memories, so she invited the nun to the top floor of the Cathedral. There, Quinella successfully overwrote the nun's Fluctlight with Quinella's own thought processes and memories. However, an unforeseen issue arose. After the Synthesis Ritual, which was used to copy Quinella's soul onto the nun's Fluctlight, was completed and the two females awoke at the same time, they came to the realization that they were identical beings, which caused both of their Fluctlights to start breaking down due to the shock caused by the realization.

However, the nun's Fluctlight was the first to break down, allowing Cardinal, the sub-process which was transferred to the nun's body in the process of the ritual, to take control of the nun's body. At that point, they recognized each other as the Administrator within Quinella's original body and the Cardinal's sub-process within the girl's body and this allowed their Fluctlights to stop breaking down.

Trivia

 * Her story is similar to Alice's. Like Quinella, Alice was very talented in the Sacred Arts. One of Alice's most well known abilities was to predict a storm one week in advance at a rather young age while Quinella was also able to predict the weather in advance, though only 3 days in advance.