The Absolute Solver in this iteration of the canon story was more akin of a "rabies" infection the humans had 'accidentally' created in a labratory while researching fatal mutations of common diseases found in animals (CWD, rabies, etc.).
Working in the labs and quite curious about this strange strain of virus, Tessa Elliott, the daughter of the lab's owner and a scientist working under her fathers orders secretly took the mutated sample home in hopes to find a solution on her own. Accidentally coming in contact with it due to this, one of the housemaids, Cyn, infects herself with the strain.
Plagued by nightmares in which a creepy hyena-looking being (seemingly trying to imitate her... and failing miserably) haunts her, whispering promises it'll keep. Infected by a terminal disease, Cyn threatens to succumb to it - but the Solver itself promises her to be cured if she allows it to take over her body after she dies.
Desperately, she agrees - and finds herself incapable of taking back the deal as her body after death is resurrected once new, with the Solver using her as attempt to create the perfect 'speciesman' to wipe out all of the "inferior" creatures on the planet. As it slowly mutated her body into a chimera-looking being Cyn can only desperatly cling to the last piece of herself she still has - her soul.