If you remember back to the first couple episodes of Season 3, Sylar had Elle pinned on the ground and tells her she more than anyone else is to blame for how he is.
At the time, that little piece of information was confusing for most of us.
Then, a few episodes later, we went back in time 6 months to when Sylar had just killed the original telekinetic, Brian Davis. He was struggling with the guilt of his recent actions -- remember the suicide attempt Elle ended?
We all know how this played out, Elle and HRG played around with Sylar (I forget the kids name, the goth-looking dude with the glass popping power.) and set him down the path to doing devilry.
So, why is this episode set 3 years ago?
Is it too much to ask for a little consistency?
(If I am incorrect about any of the timeline, I apologize.)
