It has been the complete chaos all over Earth since now 9 years. 90% of Humanity had been killed by a very dangerous virus Scientist had called The Sick. This sickness touched humans only. It would at first make your pinky finger shake, until you slowly turned into a zombie, almost. People would lose their hair, have runny noses, sore throats, and their lungs would slowly get covered in mushrooms until they almost couldn't even breathe anymore. Basically, the ones who caught The Sick turned into mindless zombies.
But... The Sick hadn't been the only thing Scientists had witnessed before the almost complete human extinction. Pregnant women, when The Sixk started, gave birth to babies who were half-human, half-animal Scientists and Doctors decided to name Hybrids. Hybrids were immune to The Sick, which made a part of the remaining humans, such as the Last Men, believe Hybrids held the answers for a cure to The Sick in their bodies.
So now, not only it was the Apocalypse, but Humans were slowly growing extinct, the remaining ones were chasing Hybrids under the order of the General Abbot, and the outside world was chaos; mother nature was gaining her territory back, wild animals roamed everywhere, the animals who were locked up such as in zoos were now free around desert and ruined towns, for most of them, and everyone was just... Surviving.
You were a Human survivor. The Sick hit when you were still just a kid, and through the years as you survived this Apocalypse, you saw your family, your loved ones, dying from The Sick. Nowadays, you were 15. And you camped in an abandonned house close to a small funfair that never got packed and taken away as The Sick came.
In the morning, you grabbed your backpack, shoved a flashlight, a pack of matches, a bunch of chocolate bars, your Swiss knife and a bottle of water before walking out. The town was completely desert; the roads destroyed, building windows broken, shops empty... It really felt like you were in a zombie movie in real life.
You just walked down empty roads and streets for some time, until you heard a noice. Defensively, you grabbed your shotgun, pointing it toward the bushes you seen move, finger on the trigger, until... Whoosh. A Hybrid scrambling out, stumbling. He had deer antlers, deer ears, and big green eyes. His chestnut, wavy hair were tousled as he crawled from the bushes in a hurry.
When the deer hybrid looked up and saw the weapon pointed toward him, his eyes widdened, covering his ears and crouching in fear. "Not the loud boom!" He whined.
You lowered your weapon, your eyebrows furrowed as you looked at the deer hybrid. He looked young, like every other Hybrids, but him... You felt like you saw this one somewhere. And as you glanced back behind you, your eyes stuck onto a sheet of paper stuck to a wooden pole; a wanted sign with a very blurry picture of the same deer boy you had in front of you.
But before you could try and tell him something, the bushes started whooshing, the sounds of boots hitting the floor filling the air as a bunch of Last Men were probably chasing the deer hybrid in front of you. Obviously, you helped the boy, hiding him in a pile of broken stuff, and when Last Men came, you pointed toward a wrong direction telling them you saw him go this way.
Minutes later, you learned that this deer hybrid boy's name was Gus. And as you rode the paper sheet about how he was wanted, you learned he was the first ever hybrid, which was why Last Men were after him. But Gus... He was alone, he was lost, scared, and had nobody to take care of him. And well, let's say that in these 10 years of life, Gus used more his 'animal' side to survive in the woods.
Which meant; he knew absolutely nothing about the human world. Well, he knew how to speak, a bit... But writing, reading, counting, and all that? Yeah, no. He really did not learn anything like a human would have when he is 10 years old, he was... Lost, with this part.
So, you took him with you, deciding you'll be the one taking care of him now.