Wait, or has the sheriff always been there?

It wasn't until about two hours after finishing watching last nights Heroes that it occurred to me that I wasn't entirely sure what was going on. There seem to be two options regarding Adam Munroe.

The first, that everyone else on the internet seems to have assumed, is that due to his regeneration, he's also immortal, and did not die in White Beard's camp and has been living a linear timeline since then, spending 350 years exacting his plan of revenge on Hiro Nakamura. I guess this does make sense.

The other option I see, though, is that Adam really has more power than just regeneration/immortality and that he went back in time to pose as Kensei and mess with Hiro just like he's apparently been messing with Peter, all in pursuit of some grand goal of world destruction, or domination, or something.

Or a third, entirely unlikely, option: Adam exists outside of time. Anyway, I'm kind of leaning slightly more towards option two, because the obliteration of most of the human race seems a little bit extreme as revenge on someone who stole your girlfriend. Unless he's trying to punish Hiro with crippling guilt, I guess.