Claire, fleeing up the bleacher steps, trips and falls as someone menacing approaches.
* In Isaac's original vision, just before Future-Hiro visits Peter on the subway train, Isaac sees the fleeing Claire stumble, rise and then turn to face the approaching Sylar alone.
* Empowered by Hiro's speech with the courage to 'save the world,' Peter defies certain death by coming to Claire's rescue. This time when she stumbles on the steps, Peter is there beside Claire to help her to her feet; together they turn to see Sylar approaching them. Peter helps Claire to escape, absorbing her regeneration ability, thus they both survive.
These moving images, contributed 3/20/07 by NBC forum member kakkarot1290, clearly demonstrate how f-Hiro's message to Peter on the subway in Episode 4 altered the future in Isaac's vision. In the original vision, we never see Peter (or Peter's shadow, clearly visible right behind Claire at Homecoming).
I guess I was right after all.
