Here's a whacked out theory for you:

Sylar is Peter from the future.

Sylar seems to have many different powers. Perhaps in the future as Peter gains better control over his powers he is able to use them at will. He also becomes evil or insane and the rest of the Heroes band together to stop him. In the moment of his defeat, Peter uses Hiro's time travel abilities to go back in time. There he starts killing all the Heroes before they band together to stop him.


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