Hiro, Peter and Claire are the two biggest examples of this.
Where'd you learn to count? ;)
It's not just Hiro and Peter...Daphne, Arthur and Sylar are all characters who would be able to time travel, And there are probably others. I do get what you mean though, They did start tying things back in towards the end there but they could take it a lot further.
Back in the beginning I got annoyed with Mohinder since he was constantly shifting back and forth. Now, it seems almost every character is guilty of this. This Villains finale tried to make this seem legitimate by giving us the 'dual' theme and the notion that everyone has the ability to be either a Hero or a Villain....
yeah I know i'm cutting out the whole Sylar thinking the Pettreli's are his parents thing.
Would that mean cutting out Sylars "oooh, cake!" line?