Oh, just a thought on the Elle & Sylar relationship, because I've rewatched some of the scenes where they are together or reacting to one another...
In "Powerless" (2x11), Elle realizes that Sylar is in Mohinder's lab. All that comprises their interaction is Elle shouting "Sylar!" and striking at him with lightning, and him running the hell away because he can't fight back.
In "The Butterfly Effect" (3x02), when Sylar attacks Level 5, Elle accuses him of killing her father and he responds by saying he's killed a lot of people, and that she is as much to blame for that as anyone.
At the time, saying that makes no sense, but I can see how they tied in that connection. I remember people saying it was nonsense.
We also don't know anything about Sylar's activities between the murders of Brian Davis and Chandra Suresh, and the murders of Molly Walker's parents.