A common theme in Science Fiction is that of the time paradox. If you go back in time and kill your grandfather, do you cease to exist? Does your ceasing to exist then cancel out the act of killing your grandfather? Do you then end up in a perpetual time loop paradox? Last night's Heroes episode introduced a question along those lines.
In an early episode in season one Peter Petrelli was visited by 'future' Hiro with a message:
'Save the cheerleader, save the world.'
Peter used this information to save the cheerleader, Claire Bennet, from the evil Sylar.
Sylar is the evil man on the show who steals the powers of other heroes by cutting their heads open and doing something with their brains.
Recently, on the show, 'present' Hiro and Ando arrived in the future and met up with 'future' Hiro, who explained that he had tried to kill Sylar in the past but failed. His failure was due to Sylar having gotten to the cheerleader and possessing her powers of regeneration. 'Future' Hiro went to explain how he went back in time to warn Peter Petrelli about the cheerleader.
At this point 'present' Hiro tells 'future' Hiro that the cheerleader was saved.
About this time everything still makes some amount of sense. It breaks down later on when we find out that the cheerleader is still alive in this timeline where 'future' Hiro failed to kill Sylar.
The key problem here is that if, when 'future' Hiro tried to kill Sylar, Sylar did have the cheerleader's powers then he should still have those powers and Claire should be dead in this time line. It's one thing to tell the audience that this future is an alternate time line, making it so Claire is alive makes it part of the true time line and causes our paradox.
If Claire is alive, why did Sylar not die when Hiro attacked him?
One possible reason for the paradox is that 'present' Hiro has not yet attempted to kill Sylar. Because of this those actions are currently in a state of flux. It may be that, because of his time-shifting/travel powers Hiro (future and present) is somehow an entity that lives outside of the time-stream continuum.
Another interesting point is that of the comic book that shows Hiro in the future and the good doctor killing the Haitian. This leads me to believe that Hiro was supposed to go in the future and see the world that happens when he fails, to give him the impetus to actually kill Sylar.
With that said, we encounter the problem of 'future' Hiro being surprised by the appearance of 'present' Hiro. If these two people were one and the same then 'future' Hiro would already know that his past self would appear in the future and that they would meet.
So, we have a big fat paradox with a few loose ropes (not strings) hanging around. All of this leads me to believe that 'future' Hiro's meddling in the past has pushed him outside of the time line at hand. Because of this he does not remember the actions that 'present' Hiro is taking because he never took them! In fact, 'future' Hiro could be said to be a visitor from an alternate dimension, a dimension where Claire dies at the hands of Sylar.
nHiro's time paradox problems were also evident went he attempted to go back in time to save the waitress Charlie from begin killed by Sylar.
We know Hiro went back in time and met her on her birthday because Ando found the photograph. We also know that Hiro and Charlie spent a lot of time together yet... Why did she not recognize him when he and Ando showed up in the Dinner?
We will have to wait until the last few episodes conclude to see just what happens. I'll be watching, will you?