Okay so anti was an experiment at cryaotic labs, I have been drawing cry as a scientist for a year now XD, so jack wasn't abused anything but he was experimented on and he didn’t like it. He wanted a normal life and stuff. So in comes mark mark is a genetically enhanced mercenary(he can't feel pain and superhuman strength), he kills for pewds who is a military weapons specialist kinda like tony stark but ya know more pewdiepie(married to marzia), so he went to kill Cry and he failed bc Jack who, he wasn’t informed about, protected him bc of a protocol embedded in his genes to protect cry which he didn’t know about.
The genes awakening in him which before had not been tested had mutated his eye and arms and sadly driven him insane (sorry anti is cray cray) but it's a split personality from jack(obviously). So he and mark had a little tussle which in my mind is awesome and then during the battle jack was struggling with anti his newly acquired abilities (telekinesis, he has regenerative abilities) he shattered glass and had it flying all around the room and it tore up crys face and scared marks eye. So that why cry wears his mask, mark has a scar across his eye and jack has a mutated eye.
Jack escaped beacause of what happened and cry was able to get away bc mark was distracted, mark reported back to Felix about jack and Felix gave marzia (the scientific brains) the blood sample mark was able to collect and a couple files on him. So they use that to try to track him down using mark….to be continued boom that's my dark and anti backstory