Tabris has done a great deal of studying in the nature of the BOR Parasites and the Oracle Cells

Compiling his own research with that of the late Gregorio Silva and Juzo Mido, he has managed to figure out quite a bit of their history, though he lacks notable details he has

managed to form a working theory, that the two species have existed almost as long as the Earth as two of the very first lifeforms to come to exist during the Cambrian Explosion

Ever since, the two single-celled organisms have been in an eternal evolutionary arms race,

constantly outpacing and devouring eachother

However, approximately a few thousand years before the great collapse the BOR parasite has managed to make an evolutionary leap ahead of the oracle cell, creating a gap between them that would never be closed, forevermore

making the parasites the one and only natural predator of the oracle cell

The evolutionary gap in question was the ability to bond with other, larger lifeforms

The parasite somehow possesses the ability to bond with a host body on a genetic level, completely taking over them

and making them into an extension of the parasite

Using the hosts body, most notably the blood, to act and grow in ways that were previously unknown to them, they overtook the oracle cell by leaps and bounds, enjoying centuries upon centuries of microscopic genocide

Of course we all know that the oracle cell did not truly become extinct all those centuries ago, but the parasites obviously assumed so and fell into dormancy, acting only in instinct and self preservation as the surviving oracle cells multiplied and evolved in secret

Very little occurred between the two for thousands of years, the two evolving side by side in quiet dormancy, that is...

Until about fifty years prior to the Great Collapse

Two things happened simultaneously, a Japanese scientist discovered an animal brought back

to life by a BOR parasite, and the oracle cells enacted their plans for revenge

Even after all this time, the parasites were still stronger than them, so they would eliminate them out with numbers

Mimicking the parasite's behavior that almost drove them into extinction, and

in lieu of the fact that they could not bond with other lifeforms, the oracle cells bonded with each other and became large existential horrors called Aragami

Even with all his research however, Tabris still hasn't figured out what caused the Great Collapse or what the

Thorns of Judgment are, but the oracle cells used the chaos to spread into the world

Even though Mido and Silva only had a limited understanding of what the BOR parasite really was, they did know enough to be able to control it's growth and development

whithin a host body, and used it to create revenants, a new breed of nearly immortal supersoldier many times more powerful than even the strongest of humans

Once they were set upon the aragami, the parasites (now the revenants) and the oracle cells (now the aragami) resumed

their evolutionary arms race, the revenants now taking the role of the aragami's natural predetors

However, this wouldn't last long, for in a desire to wipe out the aragami once and for all, the revenants created their own nightmare

The Queen, vastly stronger than any

revenant or aragami that has ever existed, the revenants quickly took to fixing their mistake

However, they would not resume fighting their natural enemy with the Queen defeated, for she could not be destroyed

Rather, her power could only be quatentined, so the revenants

walled off a portion of the world, and as they stagnated inside inside the walls, the aragami grew and evolved outside, finally overtaking their ancient rivals

However, three extraordinarily powerful aragami did get trapped in the walls with the revenants

These aragami however would one day be killed and devoured by a revenant, one who has absorbed the power of the Queen herself along with a dozen other revenants, further evolving him into one of the most powerful lifeforms the Earth has ever known