Over the course of seasons 2, 3 and 4, the writers depicted Sylar attempting at various times and under different circumstances to become a hero or curb his desire to kill, undergoing relapses at various stages.
[1] Sylar was created as a cannibal who ate his victims' brains and "digested their power"; however, in order to avoid the potential silliness and zombie associations, the producers deliberately made this fact vague in the series.
The question is addressed in the season three premiere, when he is depicted in the act of acquiring Claire Bennet's regenerative powers through examination of her brain with his hands.
Prior to Quinto's first appearance in the episode "Seven Minutes to Midnight", the role of Sylar was played by stunt doubles, and usually, as in "One Giant Leap", the character's face being obscured by shadows.
This was fueled by his mother's vocal disappointment in him for perceived failure and his own feelings that he did not get a chance to choose his destiny, being forced into the role of a watchmaker.
The episode "Six Months Ago" reveals that Sylar's real name is Gabriel Gray, a highly talented watchmaker who follows his adoptive father's footsteps.
After Peter shows up and is temporarily killed by Sylar, Mohinder knocks him out, but ends up leaving Isaac Mendez's address on the ground.
After attempting to confide in Mohinder, he returns home to his alleged mother, Virginia Gray, in the hope that she will tell him that it is fine not to be special and live as a normal watchmaker.
Against her wishes, Elle helps Noah manipulate him to kill again by introducing Gabriel to Trevor Zeitlan, a young man who can kinetically shatter objects by "shooting" at them with his thumb and forefinger.
When Gabriel realizes Elle also has an ability, he is furious and pushes her against the wall with his mind, commanding her to leave before turning on Trevor and taking his power.
She allows him to kill Bridget Bailey, a woman who can see the history of an object by touching it, in order to feed his hunger for power.
During the road trip, Noah chastises him about the murder of Jesse at the bank and his terrorizing Claire, and Sylar states that "rehabilitation doesn't happen overnight.
The power gained from Bridget enables him to experience the horror she went through, so he attempts to sincerely apologize to her, but she regards him with anger and disgust, and Bennet emphatically tells him to never to speak to his daughter again.
However, after Noah Bennet claims that Angela and Arthur Petrelli are not his real parents and are just manipulating him, Sylar feels betrayed and reverts to his murderous tendencies.
Noah releases several Level 5 inmates as bait, including Echo Demille, Eric Doyle, and Daniel Pine, but Sylar easily disposes of them.
As Sylar demands to be told the truth, Claire stabs him in the back of the head with a piece of glass, which will prevent him from reviving as long as it remains in place.
Following the destruction of Primatech, Sylar is shown to be alive and well (it's later revealed that the fire melted the glass, allowing him to regenerate), and begins to search for his true biological parents.
After taking the address from Martin, Sylar finds Samson's home, only for it to be empty and Nathan Petrelli's agents waiting to ambush him.
However, when Sylar cuts himself and heals while stuffing the rabbit, Samson transforms, reviving his hunger for abilities, desperate to gain immortality and escape from death.
Later, when Danko returns home to his apartment after discovering Nathan's ability, he finds the stuffed rabbit on his desk, unaware that Sylar is lurking in the shadows nearby.
Further examining the shapeshifting ability, Sylar realizes he is actually absorbing different DNA sequences into his body, causing him to permanently change a little each time he shifts.
While examining her collection of snow globes, Sylar unknowingly shapeshifts into his mother and begins to have a conversation with himself, showing acute symptoms of dissociative identity disorder.
When she discovers the truth, he controls her using the power which he had empathically absorbed from Eric Doyle and talks about how similar they are, both being adopted and both having the ability to live forever, proposing that, given enough time, Claire might come to forgive him and even love him.
Sylar subsequently kills Nathan (after empathically absorbing his power during the fight) and takes on the form of the President's Chief of Staff.
Sylar tries to convince a furious Matt that he's changed, but fails and begins to leave with Peter (who read Eli's mind and learned Samuel's plans).
Fearing the worst, Peter heads into the tent to find Sylar admiring his new "masterpiece": a dazed Doyle trussed up like a puppet, clad in giant light-bulbs.
Sylar's base power, as described by Chandra Suresh, is "intuitive aptitude", the ability to innately understand and manipulate patterns within complex systems, which initially manifests as a talent for repairing timepieces.
In "Fallout", Noah Bennet theorizes that Sylar's additional powers are a product of using foreign DNA to alter his own which, as a side effect, has driven him insane.
In contrast to the limited abilities Brian Davis displayed, Sylar's skills are far more advanced; he exhibits both fine control (precisely cutting open the skulls of his victims) and sheer force (flipping a police van), can enhance his own strength and durability to superhuman levels,[note 1] and can control a person's motor skills in a manner similar to Eric Doyle's puppet mastery.
In it, he kills a man named "Uncle Glen", who is apparently able to remove his fingers, failing to realize that this is a simple sleight of hand trick to impress young children.