Reaper Hounds, also just known as Monsters or Hounds, are wolf-like entities created by Persophia, tin the underground laboratories of The Quantum Order. They are large, car-sized creatures with incredibly sharp claws, powerful strength, acidic saliva, & a powerful bite. They are created by injecting adult humans with a specially created mutation serum. Children & young teens are immune to this effect. The first successful monster to be mutated was Emiko; who'd later be followed by other kidnapped humans, as Persophia sought to perfect the serum to create the strongest monsters.
The serum is partially composed of a concentrated, liquid form of Adam's magic, provided by Adam voluntarily. While Adam is aware of the experiments, he's never actually seen the process for himself, believing his mother's word that the test-subjects are volunteers. ...Which they definitely aren't.
When transformed, the person's mind is split in two- all their rage & anger is extended outwards, fuelling the hound's actions as a creature of instinct & destruction. Meanwhile, everything else about their personality & consciousness is suppressed, trapped in a simulation composed of their happiest memories. A perfect dreamworld that keeps the human inside complacent while the other half wrecks havoc on the outside world.
They can be cured using an antidote created by Zeke, Ryan, & Tyler. When cured, humans who were formerly hounds may have minor leftovers of the transformation's effects; such as tails, fangs, or in Emiko's case, coloured patches on her skin & tapetum lucidum.
Other side effects may include having stronger magical abilities with less effort; such as enhanced strength, night vision, or the ability to purr & growl.