Future!Hiro determines that the pivotal change in history that he needs to make to prevent NYC from being destroyed is to tell Peter "Save the Cheerleader, Save the World!" - because it was Claire's regenerative abilities that allowed Sylar to survive his katana wound and still explode. He goes back to his own time and discovers that that wasn't sufficient, because -Peter- exploded instead. But then he doesn't change it any further - instead, Present!Hiro goes to that timeline, and sees everything. Which means the only difference from that timeline and the show's is that Hiro went to that timeline and saw that future. So how did -that- cause the one difference that prevented that future, ie, Nathan growing a conscience and flying in to save the day? I guess he -did- go up to Nathan and cal