Sylar was Dr Suresh's blueprint to find the other heroes. He
could have some innate resilience or some other unrecorded power.
Haven't u ever noticed the cockroaches around him throughout season
1? What that truly signifies no one knows but it probably has
something to do with cockroaches being able to adapt to anything.
As for Peter, well haven't you ever had an orgasm? The first time
you do it you can't control yourself. After that it gets easier.
Anyway season 2 wasn't supposed to end this way. 
If not for the writers' strike the ending would be the Shanti virus
being released and the first victim would have been Nathan. Odessa,
Texas would be ground zero and Volume 3 would have been entitled
'Exodus' not 'Villains'.
