I haven't decided on an actual name for him just yet

In this universe, Cats are a group of species that can be basically anything. The two main requirements for something being a Cat is that they have at least two triangular ears and "The Cat Gene", which allows them to connect to the "Sacred Power of Cats" (SP). The Sacred Power is a mysteriously large pool of energy that only Cats can access, and all Cats share this energy together, though 99.99% are not even aware that its a thing. 

The Cats had suddenly spread far across the Galaxy and hunted weaker species down to absorb them while bringing great trouble to the sapient species that ruled the stars before them

One particular species of Cat is so dependent on the SP that they are more like ghosts than actual living things. These Cats are called the Phantoms, and they have a deep connection to the source of the SP. Think about scary poltergeists and the astral plane.

Phantoms grow from experience. The more experienced a Phantom is, the more they are able to tap into the SP, thus making them incredibly different from the Cats both in appearance and behavior. Most Phantoms are weak and ghostlike as they commonly haunt in one area. Experienced Phantoms are incredibly rare and powerful, and Onions was one of them.

Onions is a Phantom who managed to possess the corpse of a stillborn alien

At the time, it was considered a well known fact by any sentient being aware of the Phantoms that they could only completely possess Cats. But the alien, who resembled a praying mantis from Earth, was compatible with Onions without a shred of issue

After the invasion of the aliens' homeworld by the Cats, he was left aside for his odd appearance, along with the fact that no Cat believed that he can possess an alien creature. Some Cats even tried to kill him, despite his ability of communicating with them through the SP

Being declared an outcast by the Cats, he observed them from afar and began to despise their ways

The Cats were composed of scattered packs and gangs that preyed on the weak. It was clear that they were bound together by the SP, but none of them had tried to use it to its full potential. They instead used the heavenly Power of the Cats to aid them in their earthly, barbaric ways and be no different than predators in the wild

Despite their deep connections, the Cats were locked in never ending civil wars as they fought over territories and prey. 

The alien world would soon be taken over completely by Cats. In order to survive his early years, Onions had to live in the shadows and live as a bottom feeder, eating the leftover remains of Cats after their disputes.

After maturing, it was his goal to bring civility and order to the Cats through any means necessary, and to awaken the power that they had been misusing

STATS