There’s a distinct difference between the human known as Dr. Alexander J. Mercer and the virus known as Alex Mercer. They may look the same, hold the same voice and watch their surroundings with the same detached, cold, analytical gaze, but they’re two different people.
Dr. Alexander Mercer was born on July 16, 1979 to an alcoholic, abusive mother and a father who left either at his birth (and is presumably dead). Alexander grew up in foster care and spent the first ten years of his life in the system, all the while his mother was incarcerated for nine. Not much is known about his life between getting released into the hands of his mother (who had recently given birth to Dana Mercer, Alexander’s younger sister) and his graduation from the University of Columbia, but it is known that he spent most of his time watching after his sister, being a straight-a student and potentially learning to kickbox.
Fast forward to his employment at Gentek, where he knowingly created bioweapons which could potentially end all life on earth, spent time studying and extracting numerous tissue and nerve samples from an immortal and unhinged patient (after clearly abandoning whatever morals the average human is expected to develop) and simply stopped talking to everyone whom he couldn’t exploit for an edge against his peers. He stopped talking to his own sister for years, causing her to move to Manhattan and relentlessly search, in vain, for a man in bed with the shadiest pharmaceutical company in pharmaceutical history, only for him to show up at her doorstep when he was sure his life was potentially in danger.
Dr. Alexander Mercer is the same man who, once he was absolutely certain that Gentek was going to have him killed for his involvement in their research, stole the very virus he had created and released it in the most densely populated city on the planet, knowing full well his only family would most likely contract and die from it. Why? Because if he was going down, the entirety of the human population might as well go with him.
He was, undoubtably, the biggest piece of shit.
Alex Mercer was simply the virus he created, which got into Alexander’s body as he was shot down in Penn Station. Alex replicated his host’s corpse’s cecaying nervous system, liquefied his organs and bones, and hours after the kill was confirmed, reanimated the body. Alex heard his morticians call him ‘Alex, Mercer J’ and assumed that must be him, and he would only find out the truth three weeks from his ‘birth’.
And even with all the carnage, blood spilled and atrocities Alex would commit in the next few weeks, his creator was much, much worse. At least the man-eating viral abomination would eventually grow a conscious (through eating people).