Long before the 'Prime' Universe was created, the Great Beings wandered the cosmic void aimlessly. Eventually, they discovered each other, which led them to realize the extent of their powers. In order to express themselves, they attempted to create unique bodies for themselves, but discovered that the void would rapidly destroy their creations in a process called Entropy.

After eons of experimentation, they discovered they could open pocket universes in the dimensions of space-time below them, and proceeded to create the multiverse, an exponentially expanding series of interwoven dimensions and timelines. Once inside the multiverse, the Great Beings could create to their hearts content. Three Great Beings volunteered to stay in the void in order to anchor and conceal the multiverse from destruction. Out of respect for these Great Beings, they where called Great Sages.

Kae-Oss became fascinated by Entropy after realizing it was a force that could completely destroy information, something that was not possible from the natural physics of the multiverse. Kae-Oss began focusing on studying Entropy, and became an expert on Corruption.

Kae-Oss accompanied a group of Great Beings to the planet of Spherus Magna, to start a testing ground for their experiments. To their surprise, they encountered a native living entity, Annona, inhabiting the planet. Annona tried to feed on the dreams of the Great Beings, but found their minds too strange to do so. The Great Beings drove Annona deep underground by trying to feed on her dreams in response.

The Great Beings then created a civilization of sapient beings in their own image. This civilization was made up of the Glatorian and the Agori, who split into eight known tribes based on the elements found on the planet. The Great Beings then integrated themselves with the Spherus Magnans, and went on to become their scientist-kings. The Spherus Magnans then gave them the name 'Great Beings.' 

Led by Angonce, the 'Great Spirit Project' was started, in which he intended to create a pair of automatons to explore and gather data from the universe and automatically return it to him. With the help of the Spherus Magnans, they constructed a prototype version of these robots. However, its power source was unstable, and the prototype exploded, scattering pieces of itself across the desert of Bara Magna.

Because of this failure, the Great Beings doubled down on their experiments, instead delegating leadership of the tribes to seven newly created Element Lords. The Element Lords would soon discover Energized Protodermis leaking from the core of the planet. Seeing this as a more viable power source, the Great Beings started construction of the first robot, which Angonce would name Mata Nui. The tribes also began fighting over the Energized Protodermis, which would lead to the start of the Core War.

Once enough construction was complete on the robot, the beings Tren Krom, Artakha, and Karzahni were created and given purpose within the robot. After that, the Great Beings created a new species of bio-mechanical beings inspired by the Glatorian and Agori called Matoran, whose purpose was to maintain Mata Nui from within. After much debate, the Great Beings decided not to make the Matoran sapient, in order to prevent situations like the Core War from happening within Mata Nui. Kae-Oss was opposed to this decision.

With all preparations completed, Mata Nui was readied for launch. However, the Core War caused a chain reaction within the planet's core that split Spherus Magna into three pieces, the forest moon of Bota Magna, the ocean moon of Aqua Magna, and the desert planet of Bara Magna. Because of this, the Great Spirit Project had to be abandoned while only half completed.

Disappointed by the actions of their civilization, the majority of Great Beings left Spherus Magna. Kae-Oss and several of the Great Beings moved on to an alternate universe version of the planet, Luna Magna, to continue their experiments. Angonce deferred leadership of the Luna Magna experiments to Kae-Oss.

Kae-Oss was convinced that the Matoran species was superior to the Agori and Glatorian, and suggested populating Luna Magna with them, only made sapient. In order to prevent a similar situation to the Core War, he would create the Luna Magnan Matoran with additional light in their spirit. While Angonce was opposed to this idea, the other Great Beings went through with Kae-Oss' experiment.

Just like with Spherus Magna, Luna Magna was populated, and the Great Beings began ruling the civilization of Matoran. However, war broke out on Luna Magna over the Moonlight Energy Crystals which could be found underground.

Seeing yet another failed experiment, the Great Beings turned against Kae-Oss, ridiculing him for repeating the mistakes of Spherus Magna. This drove Kae-Oss mad, and he threatened to destroy Luna Magna in his rage. The Great Beings imprisoned him in the core of the planet to protect the Luna Magnans, then left to continue their experiments elsewhere in the multiverse.

While imprisoned, Kae-Oss discovered he could send information through the veins of Moonlight Crystals inside Luna Magna, and used them as conduits for his now limited power. He was able to manipulate the crystals to create the Luna Dial, and transform Gringat into a Toa. He would also go on the create Leimera, and deposit her on the surface of the planet. 

For many years, Kae-Oss continued to observe and influence the development of Luna Magna from the core of the planet.

Abilities & Tools

As a Great Being, Kae-Oss is from a higher plain of reality, and is able to manipulate the universe around him. This allows him to create and destroy matter, energy, and spirits, but only from within the multiverse. He is unable to die, or be killed.

As a study, Kae-Oss is fascinated by Corruption. He learned to harness the power, which mimics the effects of Entropy in a localized area. He refers to himself as the 'Great Being of Corruption.'

When Kae-Oss' power is combined with that of another Great Being, they gain the ability to imprison a Great Being within an orb of space-time, which can only be undone if two or more Great Beings combine their power again.

When Kae-Oss created the Luna Dial, he created a sibling for the artifact called the Umbra Dial. The abilities of the Umbra Dial are currently unknown.

Kae-Oss also wields an artifact which can project his powers into a burning blade. The effects of this weapon are currently unknown.

Kanohi, the Great Being of Emotion, created the Kanohi Jutlin based on Kae-Oss' appearance. The mask was given the power of Corruption, based on Kae-Oss' studies of Entropy.

Later, Kae-Oss would change his body to mimic Knoxus, and he would appear to be wearing a Kanohi Tryna, the Great Mask of Reanimation.

Personality

Like all Great Beings, Kae-Oss is highly intelligent when compared to most sapient beings, due to being from a higher plain of reality. However, his intellect is highly handicapped by his current state of rage-induced insanity.

Kae-Oss is cunning and controlling, and often tries to use brute force to manipulate certain results from experimentation. This is part of why his fellow Great Beings imprisoned him, which led to his vengeful resentment of them after he went mad. 

Trivia