Originally Posted by Tokyo Slim
There is a theory that Peter Petrelli (the guy who keeps trying to fly, even though its become fairly apparent to people with keen observational skills like us, that its not his power) will actually become Sylar (the main bad guy).
Sounds like a good theory, but I'm not sure I buy it 100%. One hole in the theory is that Sylar had a picture of Nathan Petrelli in his den of crazy - insane super-powered time-traveller or no, I don't think he'd need a picture to figure out how to find his brother, even if he has come from THE FUTURE.
Another is that Sylar had some kind of sessions with papa Suresh, prior to the start of the series, before which he didn't know what he was capable of. Doesn't really sound time-travelley - sounds more like he was just a regular old serial killer until then.
Baseless prediction no. 2: Papa Suresh is still alive somewhere - if only because we see his picture on the book jacket, and it's a name actor (Erick Avari). He'll be back in one form or another.